create_initial_theme_features() WordPress Function

function create_initial_theme_features() {
	register_theme_feature(
		'align-wide',
		array(
			'description'  => __( 'Whether theme opts in to wide alignment CSS class.' ),
			'show_in_rest' => true,
		)
	);
	register_theme_feature(
		'automatic-feed-links',
		array(
			'description'  => __( 'Whether posts and comments RSS feed links are added to head.' ),
			'show_in_rest' => true,
		)
	);
	register_theme_feature(
		'custom-background',
		array(
			'description'  => __( 'Custom background if defined by the theme.' ),
			'type'         => 'object',
			'show_in_rest' => array(
				'schema' => array(
					'properties' => array(
						'default-image'      => array(
							'type'   => 'string',
							'format' => 'uri',
						),
						'default-preset'     => array(
							'type' => 'string',
							'enum' => array(
								'default',
								'fill',
								'fit',
								'repeat',
								'custom',
							),
						),
						'default-position-x' => array(
							'type' => 'string',
							'enum' => array(
								'left',
								'center',
								'right',
							),
						),
						'default-position-y' => array(
							'type' => 'string',
							'enum' => array(
								'left',
								'center',
								'right',
							),
						),
						'default-size'       => array(
							'type' => 'string',
							'enum' => array(
								'auto',
								'contain',
								'cover',
							),
						),
						'default-repeat'     => array(
							'type' => 'string',
							'enum' => array(
								'repeat-x',
								'repeat-y',
								'repeat',
								'no-repeat',
							),
						),
						'default-attachment' => array(
							'type' => 'string',
							'enum' => array(
								'scroll',
								'fixed',
							),
						),
						'default-color'      => array(
							'type' => 'string',
						),
					),
				),
			),
		)
	);
	register_theme_feature(
		'custom-header',
		array(
			'description'  => __( 'Custom header if defined by the theme.' ),
			'type'         => 'object',
			'show_in_rest' => array(
				'schema' => array(
					'properties' => array(
						'default-image'      => array(
							'type'   => 'string',
							'format' => 'uri',
						),
						'random-default'     => array(
							'type' => 'boolean',
						),
						'width'              => array(
							'type' => 'integer',
						),
						'height'             => array(
							'type' => 'integer',
						),
						'flex-height'        => array(
							'type' => 'boolean',
						),
						'flex-width'         => array(
							'type' => 'boolean',
						),
						'default-text-color' => array(
							'type' => 'string',
						),
						'header-text'        => array(
							'type' => 'boolean',
						),
						'uploads'            => array(
							'type' => 'boolean',
						),
						'video'              => array(
							'type' => 'boolean',
						),
					),
				),
			),
		)
	);
	register_theme_feature(
		'custom-logo',
		array(
			'type'         => 'object',
			'description'  => __( 'Custom logo if defined by the theme.' ),
			'show_in_rest' => array(
				'schema' => array(
					'properties' => array(
						'width'                => array(
							'type' => 'integer',
						),
						'height'               => array(
							'type' => 'integer',
						),
						'flex-width'           => array(
							'type' => 'boolean',
						),
						'flex-height'          => array(
							'type' => 'boolean',
						),
						'header-text'          => array(
							'type'  => 'array',
							'items' => array(
								'type' => 'string',
							),
						),
						'unlink-homepage-logo' => array(
							'type' => 'boolean',
						),
					),
				),
			),
		)
	);
	register_theme_feature(
		'customize-selective-refresh-widgets',
		array(
			'description'  => __( 'Whether the theme enables Selective Refresh for Widgets being managed with the Customizer.' ),
			'show_in_rest' => true,
		)
	);
	register_theme_feature(
		'dark-editor-style',
		array(
			'description'  => __( 'Whether theme opts in to the dark editor style UI.' ),
			'show_in_rest' => true,
		)
	);
	register_theme_feature(
		'disable-custom-colors',
		array(
			'description'  => __( 'Whether the theme disables custom colors.' ),
			'show_in_rest' => true,
		)
	);
	register_theme_feature(
		'disable-custom-font-sizes',
		array(
			'description'  => __( 'Whether the theme disables custom font sizes.' ),
			'show_in_rest' => true,
		)
	);
	register_theme_feature(
		'disable-custom-gradients',
		array(
			'description'  => __( 'Whether the theme disables custom gradients.' ),
			'show_in_rest' => true,
		)
	);
	register_theme_feature(
		'editor-color-palette',
		array(
			'type'         => 'array',
			'description'  => __( 'Custom color palette if defined by the theme.' ),
			'show_in_rest' => array(
				'schema' => array(
					'items' => array(
						'type'       => 'object',
						'properties' => array(
							'name'  => array(
								'type' => 'string',
							),
							'slug'  => array(
								'type' => 'string',
							),
							'color' => array(
								'type' => 'string',
							),
						),
					),
				),
			),
		)
	);
	register_theme_feature(
		'editor-font-sizes',
		array(
			'type'         => 'array',
			'description'  => __( 'Custom font sizes if defined by the theme.' ),
			'show_in_rest' => array(
				'schema' => array(
					'items' => array(
						'type'       => 'object',
						'properties' => array(
							'name' => array(
								'type' => 'string',
							),
							'size' => array(
								'type' => 'number',
							),
							'slug' => array(
								'type' => 'string',
							),
						),
					),
				),
			),
		)
	);
	register_theme_feature(
		'editor-gradient-presets',
		array(
			'type'         => 'array',
			'description'  => __( 'Custom gradient presets if defined by the theme.' ),
			'show_in_rest' => array(
				'schema' => array(
					'items' => array(
						'type'       => 'object',
						'properties' => array(
							'name'     => array(
								'type' => 'string',
							),
							'gradient' => array(
								'type' => 'string',
							),
							'slug'     => array(
								'type' => 'string',
							),
						),
					),
				),
			),
		)
	);
	register_theme_feature(
		'editor-styles',
		array(
			'description'  => __( 'Whether theme opts in to the editor styles CSS wrapper.' ),
			'show_in_rest' => true,
		)
	);
	register_theme_feature(
		'html5',
		array(
			'type'         => 'array',
			'description'  => __( 'Allows use of HTML5 markup for search forms, comment forms, comment lists, gallery, and caption.' ),
			'show_in_rest' => array(
				'schema' => array(
					'items' => array(
						'type' => 'string',
						'enum' => array(
							'search-form',
							'comment-form',
							'comment-list',
							'gallery',
							'caption',
							'script',
							'style',
						),
					),
				),
			),
		)
	);
	register_theme_feature(
		'post-formats',
		array(
			'type'         => 'array',
			'description'  => __( 'Post formats supported.' ),
			'show_in_rest' => array(
				'name'             => 'formats',
				'schema'           => array(
					'items'   => array(
						'type' => 'string',
						'enum' => get_post_format_slugs(),
					),
					'default' => array( 'standard' ),
				),
				'prepare_callback' => static function ( $formats ) {
					$formats = is_array( $formats ) ? array_values( $formats[0] ) : array();
					$formats = array_merge( array( 'standard' ), $formats );

					return $formats;
				},
			),
		)
	);
	register_theme_feature(
		'post-thumbnails',
		array(
			'type'         => 'array',
			'description'  => __( 'The post types that support thumbnails or true if all post types are supported.' ),
			'show_in_rest' => array(
				'type'   => array( 'boolean', 'array' ),
				'schema' => array(
					'items' => array(
						'type' => 'string',
					),
				),
			),
		)
	);
	register_theme_feature(
		'responsive-embeds',
		array(
			'description'  => __( 'Whether the theme supports responsive embedded content.' ),
			'show_in_rest' => true,
		)
	);
	register_theme_feature(
		'title-tag',
		array(
			'description'  => __( 'Whether the theme can manage the document title tag.' ),
			'show_in_rest' => true,
		)
	);
	register_theme_feature(
		'wp-block-styles',
		array(
			'description'  => __( 'Whether theme opts in to default WordPress block styles for viewing.' ),
			'show_in_rest' => true,
		)
	);
}