With bitcoin, not your keys, not your coins. Now if someone demands your private seed phrase because for this or that reason, do not hesitate to call him an impostor, a fake, trusted friend. No one deserves to know our own private keys but only our own selves, so if he breaks that, obviously he's into something, to steal what you have in your wallet.
Some even promise guaranteed high returns, that's very unlikely with bitcoin. Bitcoin is too volatile and unpredictable, you can't even tell when you are going to make your first profits due to bitcoin's volatile issues.
This is why understanding the basics of bitcoin and wallets is good, because no matter how a scammer pretends to be genuine, it will get to a point where they want to play the game, and one will just understand what the scammer is up to. What these scammers do is come across as genuine to teach or solve problems related to bitcoin; they try to build that trust first.
After achieving this, they request one's seed phrase, and for someone who doesn't understand what a seed phrase is all about and how it should be handled, it will end up becoming a victim. But if the understanding is there, it is very difficult to fall for scammers, no matter how hard they try to deceive someone.