WordPress at a glance
function is not described

register_block_style() WP 5.3.0

Registers a new block style.

No Hooks.

Return

true|false. True if the block style was registered with success and false otherwise.

Usage

register_block_style( $block_name, $style_properties );
$block_name(string) (required)
Block type name including namespace.
$style_properties(array) (required)
Array containing the properties of the style name, label, style (name of the stylesheet to be enqueued), inline_style (string containing the CSS to be added).

Changelog

Since 5.3.0 Introduced.

Code of register_block_style() WP 5.7.2

<?php
function register_block_style( $block_name, $style_properties ) {
	return WP_Block_Styles_Registry::get_instance()->register( $block_name, $style_properties );
}