(not sure how it's called)

I think you are looking for "wealth tax"

Also the US has inheritance tax that kicks in once an estate exceeds 5million dollars. The problem is that you can bypass that limit by establishing a trust that holds all your assets. If before your death you put everything over 5million in a trust (baisically a legal contract that acts like a container for assets that a lawyer oversees to make sure the contract is executed) then it stops being your wealth and starts being the trust's wealth. A trust can have any arbitrary set of rules, for example it could be as simple as: wisely invest my assets and pay out an income to my surviving decendants from the intrest and their decendants. Or ot could be: while i live pay me out, on my death distribute everything left to charities my children are ungreatful brats and don't get anything. Really it can be anything.

Those are really useful if for example you have 3 unmarried adults who want to share property and make sure property rights transfer between them until everyone is dead then the trust is disolved and the property goes to: favorite niece or something. It can also be useful to allow joint ownership of regulated items that otherwise can't be jointly owned (e.g. machine guns) they are also more powerful than a will if for example you want to make sure your grandkids get college money, or dont get any money until 25, while their parents get nothing and so on... anything you can put on a contract can rule the trusts assets.

So realistically the solution here is to cap how much value can be in a trust, say 5million dollars, and limit how many trusts an individual can be a benneficiary of, lets say 3 trusts at a time.

Gift taxes

taxing inheritence and transfer of assets

Wouldn't happen in CA. As blue as they seem, prop 13 makes them basically a feudal society with actual landed gentry. I'm not making that up.