Custom post and comments not closing

You would only need to add your post type as a valid post type for this. See: https://github.com/WordPress/WordPress/blob/b8438bdcbb786bbcb4a53968c089dce7f76a0d09/wp-includes/comment.php#L3364

There is this hook for that: https://developer.ww.wp.xz.cn/reference/hooks/close_comments_for_post_types/

As far as I understand you, you have created a custom post type and want to activate the “closing of comments after 14 days” provided by WordPress. To do this, you must use the above hook to integrate your custom post type in the auto-close feature. It should look something like this:

add_filter( 'close_comments_for_post_types', function( $list ) {
 $list[] = 'your_post_type';
 return $list;
});

You must of course replace “your_post_type” with the slug of your custom post type.

If you have created the custom post type with a plugin, you have the option of either storing the above-mentioned code in the functions.php of your child theme or using a code snippet plugin OR asking the support of the plugin you used to create the custom post type for help.