The real question here is not about the Universe per se, but about our perception of it. In other words how do we start talking about a Universe at all?
And the answer to that in my opinion is General Schemas Theory, i.e. that we project many different templates of understanding on Spacetime and the Universe is one of them.
The series of schemas are something like this:
F theory (two orthogonal time lines)
OpenScape (meta-system. environment, context, ecosystem, epigenome, media etc.)
Since each of these schemas are “systems” and the next higher one into which it is nested is a “meta-system” then the answer is that the Pluriverse, or Multiverse, or Many Worlds is the next higher schema up into which the Universe or Kosmos is nested and so what is Before (outside, beyond) the Kosmos as universe is the Pluriverse, or Multiverse that the many worlds theory and string theory posits. The Pluriverse is up to ninth dimension, and so string theory and even higher dimensional versions of it like M and F theory are unschematized for us.