wp-content/themes/twentytwentyone/inc/block-styles.php:20Registers block styles.
void function twenty_twenty_one_register_block_styles() { // Columns: Overlap. register_block_style( 'core/columns', array( 'name' => 'twentytwentyone-columns-overlap', 'label' => esc_html__( 'Overlap', 'twentytwentyone' ), ) ); // Cover: Borders. register_block_style( 'core/cover', array( 'name' => 'twentytwentyone-border', 'label' => esc_html__( 'Borders', 'twentytwentyone' ), ) ); // Group: Borders. register_block_style( 'core/group', array( 'name' => 'twentytwentyone-border', 'label' => esc_html__( 'Borders', 'twentytwentyone' ), ) ); // Image: Borders. register_block_style( 'core/image', array( 'name' => 'twentytwentyone-border', 'label' => esc_html__( 'Borders', 'twentytwentyone' ), ) ); // Image: Frame. register_block_style( 'core/image', array( 'name' => 'twentytwentyone-image-frame', 'label' => esc_html__( 'Frame', 'twentytwentyone' ), ) ); // Latest Posts: Dividers. register_block_style( 'core/latest-posts', array( 'name' => 'twentytwentyone-latest-posts-dividers', 'label' => esc_html__( 'Dividers', 'twentytwentyone' ), ) ); // Latest Posts: Borders. register_block_style( 'core/latest-posts', array( 'name' => 'twentytwentyone-latest-posts-borders', 'label' => esc_html__( 'Borders', 'twentytwentyone' ), ) ); // Media & Text: Borders. register_block_style( 'core/media-text', array( 'name' => 'twentytwentyone-border', 'label' => esc_html__( 'Borders', 'twentytwentyone' ), ) ); // Separator: Thick. register_block_style( 'core/separator', array( 'name' => 'twentytwentyone-separator-thick', 'label' => esc_html__( 'Thick', 'twentytwentyone' ), )Introduced in Twenty Twenty-One 1.0. Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
src/wp-content/themes/twentytwentyone/inc/block-styles.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.