Сергей

add_filter('posts_search', function( $search, \WP_Query $q ) {
    if (!is_admin() && empty($search) && $q->is_search() && $q->is_main_query())
        $search .=" AND 0=1 ";

    return $search;
}, 10, 2);

add_filter('jpeg_quality', function($arg){return 100;});