WordPress at a glance
filter is not described

site_icon_image_sizes filter-hook . WP 4.3.0

Filters the different dimensions that a site icon is saved in.

Usage

add_filter( 'site_icon_image_sizes', 'filter_function_name_405' );
function filter_function_name_405( $site_icon_sizes ){
	// filter...

	return $site_icon_sizes;
}
$site_icon_sizes(array)
Sizes available for the Site Icon.

Where the hook is called

WP_Site_Icon::additional_sizes()
site_icon_image_sizes
WP_Site_Icon::intermediate_image_sizes()
site_icon_image_sizes
wp-admin/includes/class-wp-site-icon.php 151
$this->site_icon_sizes = apply_filters( 'site_icon_image_sizes', $this->site_icon_sizes );
wp-admin/includes/class-wp-site-icon.php 187
$this->site_icon_sizes = apply_filters( 'site_icon_image_sizes', $this->site_icon_sizes );

Where the hook is used (in WP core)

Does not used.