public function enable_custom_image_sizes($sizes)
    {
        // Merge custom sizes into $sizes.
        $sizes = \array_merge($sizes, $this->size_dropdown_names);

        // Ensure 'Full size' is always at end.
        unset($sizes['full']);
        unset($sizes['thumbnail']);

        if (Config::get('images.insert_image_allow_full_size') || empty($sizes)) {
            $sizes['full'] = 'Full Size';
        }

        return $sizes;
    }