您可以首先尝试以下注释查询：

$comments = get_comments( 
    [
        \'post_type\'     => \'projects\',
        \'post_status\'   => \'publish\',
        \'type\'          => \'message\',
        \'date_query\'    => [
            [
                \'before\'    => \'5 days ago midnight\', 
                \'inclusive\' => true,
            ]
        ],
        \'meta_query\'    => [
            [
                \'key\'   => \'foo\',       // <-- Adjust to your needs!
                \'value\' => \'bar\'        // <-- Adjust to your needs!
            ]
        ]           
    ] 
);

$post_ids = array_unique( wp_list_pluck( $comments, \'comment_post_ID\' ) );

然后，您可以将其用于：

$query = new WP_Query( [ \'post__in\' => $post_ids, ... ] );