Only in real life, not in any of the marketing materials. So you only know how it really works after purchase.

Which foldable do you own? There is no visible crease on my Fold 7 during normal use. The only way I can see it is by placing the phone directly under a light and angling it in an unnatural direction.

That said, my old Fold 4 had an obvious crease. But it's no longer an issue with modern foldables.