What happens to a creature that changes size inside of Otiluke's Resilient Sphere?

If one was to reduce a creature, making them smaller and then casting Otiluke's Resilient Sphere around them, what would happen when reduce has ended?

Would the creature get crushed by the sphere due to becoming big again, or would the sphere enlarge itself? If they would take damage, how much and what type?

• Try this query: enlarge reduce [dnd-5e][spells] is:question. The brackets are for specifying tags, and the is:question should be obvious. That being said, have a look at this: What happens to the target of a Reduce spell if they are in a small container when the spell wears off?. I'm not sure if it's a duplicate, though, since Otiluke's Resilient Sphere is not your average "small container". – PixelMaster Mar 22 '19 at 15:56
• I have looked at that question and it answers a variant of my question in cases if the creature is locked withing a physical container, be it stone, glass, metal, but the sphere is apparently indestructible via physical damage, so it wouldn't really collapse or burst open, and even if it were to be destroyed what type of damage would the creature take? magic, bludgeoning? – Vist Mar 22 '19 at 16:00
• – Rubiksmoose Mar 22 '19 at 16:40

The sphere should change size

Otiluke's Resilient Sphere says:

The sphere is weightless and just large enough to contain the creature or object inside.

Though not explicit, nothing in this description implies that the size is static and that the sphere won't adjust to a creature of changing size. It states that the effect is large enough to contain the creature. The effect of this spell is ongoing. If the creature changes, the size of the sphere must also for this statement to remain true.

Thus, if the creature's size changes (as long as it remains Large or smaller), the sphere would adapt to the new size. No damage would thus be taken.