Due to the nature of how it works, High 1-A+ has similar properties to Tier 0, in a way. For instance, all characters in that tier are exactly equal. You can't really be above the collection of all possibilities and yet be, yourself, one of those possibilities, as that'd be an obvious contradiction. So ultimately, transcending a High 1-A+ means you're Tier 0, and if you supposedly do that while also displaying traits very unlike those of a Tier 0, then the thing you transcended was just never High 1-A+ to begin with.
Furthermore, a character "blowing up all possibilities," or something to that effect, is likewise incoherent. That is because a High 1-A+ space would be, in effect, the collection of all possible contingencies: All the things that aren't necessarily true, but aren't necessarily false, either. For example, your existence is a contingency, because it could have been that you never came into existence.
So, if a character blew up all possible worlds, and this was a contingent event, then there would be a possible world where... they... didn't do that. That's an obvious paradox, so, yeah, doesn't work at all, either. The only way to be High 1-A+ is to be the embodiment of all possibilities yourself