Can I automatically add a new user to a group?

I completed this with the following code added to functions.php in my child theme.

/* based on code from: https://www.ads-software.com/support/topic/plugin-page-security-by-contexture-time-line-for-users?replies=2 */
/* auto adds new users to group 3 */
add_action(‘user_register’,’autoregister_user’,10,1);
function autoregister_user($user_id){
$group_id = 3;
CTXPS_Queries::add_membership($user_id,$group_id);
}