There is no reason California cannot divide itself into six different governmental entities for all in state purposes, but they would still only get two U.S. Senators.
Interesting point, but why do you say that?
Would like to learn more, what advantages there are to dividing into 6 states. It could actually help the GOP in presidential elections, as 2 or 3 of these new states might vote Republican and get at least some electoral votes from California.