Always use for post images
You can try the image_send_to_editor filter: /** * Wrap the inserted image html with <figure> * if the theme supports html5 and the current image has no caption: */ add_filter( ‘image_send_to_editor’, function( $html, $id, $caption, $title, $align, $url, $size, $alt ) { if( current_theme_supports( ‘html5’ ) && ! $caption ) $html = sprintf( ‘<figure>%s</figure>’, $html … Read more