Different theories are fun to read. I would like to add that my source for this is people's experiences because when I searched," schizophrenic experiencing alternate dimensions " this is the type of shit that comes up! They used dimensions as a vocabulary word!

Psychological Dimensions Relevant to Motivation and Pleasure in Schizophrenia

https://www.frontiersin.org/articles/10.3389/fnbeh.2022.827260/full

https://www.quora.com/Is-it-possible-that-schizophrenics-are-not-actually-crazy-but-are-able-to-access-other-dimensions

In 2016 this was not the way it was referred.

Mysticism and schizophrenia: A phenomenological exploration of the structure of consciousness in the schizophrenia spectrum disorders

https://www.sciencedirect.com/science/article/pii/S1053810016301088