I don't think salary caps are necessary. Just having steeper tax brackets will eventually lead to a soft cap, while not feeling like a punishment. Maybe even a simple function instead of brackets, its more dynamic and easier to calculate.

Wealth tax is kinda weird, since first someone needs to estimate the wealth, which is not easy. Then the amount to be paid probably needs to be cash, since 20% of e.g. a house is pretty useless. But actually liquefying enough wealth can have wild effects. For example Tesla stock plummeted for a while due to elon needing twitter-money.

In a sense it could prevent companies from growing. If I own a company imma make sure it stays below the threshold, since I don't want to sell my shares and loose voting-rights.

Or if you look at countries trying to seize Russian oligarchs' property: A lot failed, due to no one knowing who actually was the owner.