Expose Custom Image Sizes in Image Block

<?php
/**
 * Allow custom images within block editor
 */
add_filter( 'image_size_names_choose', 'wd_custom_image_sizes' );
function wd_custom_image_sizes( $sizes ) {

     return array_merge( $sizes,
          [
               'cervicide-thumb' => __( 'Cervicide Thumbnail', WD_THEME_SLUG ),
          ]
     );
}