The universe is not expanding as such, it is a dimensional reality which means it is not endless not spatial, just is made up of endless dimensions which interact with each other.<quoted text>
That is a possibility, yes. At this point, we don't have the evidence to say whether the universe is infinite in spatial extent or not. At the very least, it is several times as large as the observable part.
It's fantasy but to my mind the best example of the universe is the Tardis in doctor Who, dimensions within dimensions giving the impression of space restriction and endlessness.