Grand Reality
Everything is within Grand Reality. It is what you might call the Multiverse--a vessel that holds all that is and all that can be imagined. It is a strange sort of thing, for it does not itself have a physical form, so there is no easy way for you to visualize it. Travel between universes is instant, for there is no real space between realities--only connections. Even I do not fully understand the nature of those connections, though I do have strong hypotheses I have yet to disprove. If there is any reliable way to imagine the Multiverse, it is as a nigh-infinite web of connections. I can discuss all this later, though.
I say anything that can be imagined lies within Grand Reality because I see no bounds to what a universe can be. The exact rules that govern each reality tend to be semi-random in the sense that the physical laws seem to have no rhythm to them, but the more similar universes are, the closer they are in connection-space.
As a result, travelling through Grand Reality is a colorful and incredibly varied experience. I have been on this journey for many, many times the age of the current cycle of our universe. There is no visualization that can do it justice. Even if you removed an atom from the Earth every billion years until there was no planet left, you would not reach the raw number of years I have been gone from this universe. And only the barest fraction of Grand Reality has revealed itself to me in that time.
There is really not much else than that. I could conjure up elaborate metaphors about its structure, but I feel that would do little justice to helping you accurately imagine it. Language is terribly weak at times, no matter how hard one tries. Whatever image you have in your mind right now is probably as close as I will be able to get it.
So with that do I end this page. There are plenty more details to discuss on how the Multiverse operates on a finer level, but those topics can have their own pages. They are listed in the sidebar for convenience.
There's a video out on my Uluscri channel basically going over all I wrote above, but with a little more detail, and a Minecraft build to help visualize everything. Here's the link.