How much could a multi-billionaire whale manipulate an altcoin to their advantage if they wanted to?

Sorry if this is a dumb question that I should already know the answer to but I'm curious... explain it to me like I'm five, if you will.

I'm talking like Elon Musk money... someone with damn near unlimited money to play with. Let's say he decided to manipulate Arbitrum, which currently has a 1.7B market cap.

I know it would involve him driving the price up then dumping but how exactly would he go about manipulating for a longer period of time? Are there any measures in place like in the stock market that keeps a person from buying too much?

I'm just basically curious as to the damage someone with this type of money could do if they wanted to, and how they would go about doing it.