In a multiverse, there are infinite possibilities. In the fifth dimension, anything that could have happened, has happened, in a different fifth-dimensional coordinate, in a different parallel universe. Additionally, in the sixth dimension, even events that could not have happened according to cause and effect, actually did happen.
This means that if there is a multiverse, anything, any imaginable reality, exists in parallel universes. In the fifth dimension, every decision point in time and space splits the current timeline into different alternate realities, where all possibilities are realized in different universes, according to decision outcomes. Furthermore, in the sixth dimension, all possibilities, not just the ones based on the current timeline, are realized in the multiverse, in different parallel realities.
For example, If I throw a dice, I open a decision point with six possible outcomes (the numbers 1 to 6). In the four-dimensional world of time and space, this dice is a (3D) cube moving and changing its position along the timeline. It lands on the table and shows a particular number, for instance 1, at this specific point in space, at this given point in time. However, it could have shown other numbers between 2 and 5. The multiverse theory says that actually, the dice shows all 6 numbers at the same time at the same place, in superposition - in different possible timelines that exist in parallel, even if in the particular timeline I am in, it shows specifically the number 1.
As another example, even if a five-dimensional dice shows all 6 numbers at the same time at the same place, it could not show the number 7. This point is not accessible by a five-dimensional coordinate system for space, time, and events. If we add a sixth dimension, we could theoretically point to a version of this dice which is impossible in a causal space-time-event-continuum. The dice could show the number 7 by transforming into an object with 7 faces.
