I would say make a setting for them to choose a php approved timezone then just use carbon to show the DB timestamps in their timezone
$myobject->created_at->timezone($this->auth->user()->timezone);
If it is created_at or updated_at then it will be a Carbon object. if you choose another column name be sure to add it to protected $dates on the model so it becomes a Carbon object and can be mutated.
protected $dates = ['my_custom_date'];
It's either ->timezone('mytimezone') or ->setTimezone('mytimezone')
Or do what I do on all my projects and don't mess with the headache of timezones and just show a friendly version like - 1 week ago, or 3 minutes ago with
$myobject->created_at->diffForHumans();
but again, needs to be carbon object.