How to get the cdn url?

Hello I’m aware that I can pull off the image of a post and then display a download image link under the post, but I get the casual download link from my website.
How to reach the CDN version of the image ?
Thank you!

function my_download_featured_image_link_after_content( $content ) {
  if ( is_singe() || has_post_thumbnail() ) {
    return $content . sprintf(
      '<a class="download_image" href="%s">%s</a>',
      esc_url( get_the_post_thumbnail_url(null, 'full') ), 
      esc_html__( 'Download featured image', 'textdomain' )
    );
  } else {
    return $content;   
  }
}
add_filter( 'the_content', 'my_download_featured_image_link_after_content' );