The Universe is growing in spatial extent, since, on an intergalactic scale, distances are increasing. Even if the Universe is infinite in spatial extent, the distances between any two galaxies is finite, and so, one has Cantor's concept of "infinities within infinities":
https://blogs.scientificamerican.com/the...thematics/
A Universe that is an "actual infinite" in space and time is completely reasonable.
https://blogs.scientificamerican.com/the...thematics/
A Universe that is an "actual infinite" in space and time is completely reasonable.