Set Profile Privacy = "who can see profile" to Friends only

privacy.php

<?php
/* Set default values for privacy in new accounts
 *
 * Set Profile Privacy = "who can see profile" to Friends only
 */
add_action("um_registration_complete","custom_um_user_registration_complete", 1);
function custom_um_user_registration_complete( $user_id ){
    update_user_meta( $user_id, "profile_privacy", "Friends only");
}