Anecdotes and Analogies
Introduction
When I did my brief pass through college (one of several attempts), I remember having to make this presentation about Quantum Computing, I kind of focused it the wrong way, and rather talked about Quantum Mechanics. The point of that story is that, during that presentation my research on Quantum Mechanics made me come up with a few extrapolations between the quantum world and the subjective human experience.
Particle Analogy
Like a particle that hasn't been observed yet, a human is born "undefined", not really a blank slate, but rather a tapestry of possibilities that could be yet are not, and it is through their interaction with the environment, that the human "particle", "de-coheres" into a defined state. Now, this is just an analogy, not science, but I see it as a useful mental exercise to further understand the nature of our world and experience.
Quantum Decision Tree
What I define as the Quantum Decision Tree is an array of options that our consciousness has access to at any given moment, a "Superposition of Opportunities", possible realities for the consciousness to choose to be in.
Multiverse as a Mechanism for Enabling "Shared" Free Will
In a reality where the Quantum Decision Tree exists, and every Unit of Consciousness has available to them a Superposition of Opportunity module to pick a next state to be in from, this would, in a way, mean that one affects reality by thinking. Nonetheless, this would presumably affect the capacity for freedom of choice of outcomes of the other Units of Consciousness that cohabit your "universe" and thus undermine the creation of free will and the stability of a deterministic reality.
So, what the Multiverse would be in this scenario, would be a set of similar universes, one for each option available to each Consciousness Unit in any particular universe, and what we do when we experience subjective thoughts, and make decisions, is to "pick" in which universe of our available set we "fall into" next. One could then also make the intuition that we can't really affect "the future" of reality as a whole, but rather we just choose a "state to be in" and that makes us fall into a reality in which it's valid for us to be in that state.
Which would mean that, thinking you have superpowers wouldn't work, but constantly thinking things will go well might push you towards realities in which it makes sense to fit that state.
In this scenario, what we are doing moment to moment is really "traveling" reality to reality, Consciousness Units who envision a future similar to the one we do, would end up in "adjacent" universes, and ones who don't would end up in far away universes, where you might still exists, but inhabited by a CU that chose decoherence towards different paths than yours, same way they might still exists in your universe, but you're truly meeting a "different" consciousness that's the same "human".
Meta-multiverse
The Meta-multiverse would be the "seed" from which all the branches originate, defining the basic laws of that set of universes, and perhaps all areas of the universes that are uninhabited by consciousness, and thus remain 'unobserved" are all still rendered in the Meta-multiverse layer, and are only drawn multiple times in the sub-layers of the multiverse if variations to those locations happen, one could thing about the Meta-multiverse as the trunk of a tree with each branch being a multiverse, and consciousness flowing upwards from the trunk.
The decisions of the consciousness units would trigger the Meta-multiverse to create new branches, and that would be how this entity "grows and evolves".
This is all in the realm of speculative science though experiments (not based on actual research).