How do Shrink and Enlarge work in constrained environments?

Question

What happens if you cast a shrink spell on an ogre then lure it to a very narrow tunnel then dispelling first spell and casting enlargement? Does that ogre explode? deforms? just gets stuck? or nothing at all?

Answer 1

Assuming you're talking about reduce and enlarge person, consider this part of the second spell:

If insufficient room is available for the desired growth, the creature attains the maximum possible size and may make a Strength check (using its increased Strength) to burst any enclosures in the process. If it fails, it is constrained without harm by the materials enclosing it— the spell cannot be used to crush a creature by increasing its size.

Technically the rules are silent on whether you could crush a creature by removing reduce person, but unless they were already squeezing through a small space, there's no way they'd be crushed anyway.