how to add custom icon as menu icon in wordpress programmatically code example

Example: wordpress menu add icon

add_filter( 'menu_image_default_sizes', function($sizes){
  
  // remove the default 36x36 size
  unset($sizes['menu-36x36']);
  
  // add a new size
  $sizes['menu-50x50'] = array(50,50);
  
  // return $sizes (required)
  return $sizes;
  
});