Well, then I guess they wouldn’t be allowed to wear them backwards.

Glasses actually make everything we see smaller, though the effect is lessened the closer the glasses are to the correct distance from our eyes. And the reason glasses change the perceived size of the wearers’ eyes is because they specifically are bending light to change how it hits our eyes.

If the glasses are for someone who is farsighted, they make their eyes look bigger, if they are to correct nearsightedness, they make the eyes look smaller.

And actually, despite what I say in my first sentence, they don’t even make stuff bigger when you wear them backwards. That effect is limited to the distance eyes are away from the lenses normally, beyond that things are actually still smaller even when looking through them backwards. How much smaller depends on how far they are from your eye.