I’m sorry to say that ‘Reality Shifting’ isn’t really a thing. Or at least it doesn’t shift realities.
It’s basically just a new name for lucid dreaming. It’s a state where you’re in a kind of half awake/half asleep state. You’re asleep enough that things feel real but awake enough that you can control to a certain extent what happens.
In psychology, there is something called “false memory”. This is when you can make someone believe that he lived and experienced something that, in fact, never happened.
Thus, it becomes a type of “reality shifting”. Check it out!
From what I understand, shifting is a type of transliminal experience which is somewhat related to lucid dreaming. So you aren’t actually going into another reality, your brain is creating that experience for you. I think that in theory, anyone can get to that state of consciousness.