In most counties in California you are free to buy land.
After that, just expect to pay property taxes unless you have money to build exactly the home they sign off on.
I once was ready to buy a reasonable small piece of land in Bolinas after graduating from college. I should have known the price was too good.
When I called the seller he took pity on me when I told him I wanted to just use it to pitch a tent on until I saved more money.
He said, "Son---you can't even put an blanket on "your" land and take a nap."