Well, depends on whether you can use the universes as measuring sticks for distances in the depiction or not.
Usually, you can not, because they are depicted as floating bubbles or lines or whatever which don't really depict proper size, and in that case I would say no to all of them. If you can use them in a way to measure the size of the 5D space to prove it's significantly large, then you could get somewhere. But... yeah, depicting 5D space in a way that conserves size is just pretty hard.
Space being infinite in itself doesn't matter, as space at that level is infinite in some sense anyway. You would need to be told that either specifically its 5 dimensional volume is infinite or that specifically the 5th dimensional axis (the one you add to the standard timelines) is infinite (or very large) for that to work. But I figure if you have information that specific then you wouldn't need this thread. In general, infinite could mean infinite by 3D or 4D standards, or in the sense of countably infinite times larger than a spacetime continuum, so that is just not enough.
And of course, countable x countable = countable, so infinite infinite multiverse structures do nothing to enhance 2-A.
As for whether above baseline 2-A exists: In a fiction it's plausible. I can absolutely see that some fiction would write that a character destroying 1 infinite multiverse is weaker than a character destroying that and another 1000 infinite multiverses. However, we factually know that in reality there is no real difference between the number of universes destroyed. It's like 1, 2, 3, 4, 5.... and 0, 1, 2, 3, 4, 5... are the same amount of numbers, but the latter list contains 0 and hence clearly "one more". Things can be larger in some sense, without being larger in a way that registers for the tiering system.
Busting more multiverses in itself is no greater feat at all for a start, but some fictions will explicitly insist that there are power differences (Like, being 2x as strong as a 2-A character). In that case, you can have 2-A Character A and have a Character B that is stated to be much stronger, but B would still be 2-A. Given that the difference isn't objective one could debate whether it holds any value when comparing it to ratings of different fictions... I think by precedence we assume it does.
But yeah, the main point is any 2-A feat will be equal, you can at best have scaling chains to get higher and, if you do, those won't get you Tier 1.