Allow Comments by Default for Multiple Post Types

function default_comments_on( $data ) 
{
    $myCustomPostType = array("my_custom_post_type_1", "my_custom_post_type_2", "contacts"); /* Custom Post Type Array */

    if (in_array($data['post_type'], $myCustomPostType))
    {
        $data['comment_status'] = 'open';
    } 

    return $data;
}
add_filter( 'wp_insert_post_data', 'default_comments_on' );

Add this code in functions.php