Yes! You can't access the true ending until you pass the end card of whatever route you're on. Even if you've seen the ending before, you have to pass the end card before you can get the prompt for the true ending.
So for example, if you want to get the true ending on Reginald's route, you would play through his route as normal, all the way until the end. Then, once the end card that says "Good End" or "Bad End" has faded, you should be met with a choice prompt that asks if you want to see the True Ending.
You can get the True Ending with either a Good End or a Bad End, but you have to play through that ending first. I hope this helps!