您可以添加自定义tax_query ，并将搜索查询传递给它：

function searchfilter($query) {

    if ($query->is_search && !is_admin() ) {
        $s = $query->get( \'s\' );
        $query->set(\'post_type\', [ \'lesson\', \'series\' ] );
        $query->set( 
            \'tax_query\', 
            [
                [
                    \'taxonomy\' => \'your-taxonomy\', 
                    \'field\'    => \'name\', 
                    \'terms\'    => $s ,
                ] 
            ] 
        );
    }
    return $query;
}

add_action(\'pre_get_posts\',\'searchfilter\');