What’s the end game to this telegram scammer?

I got a random telegram message from someone asking if they could buy my old Coinbase wallet to use for a ICO project. I haven’t used the wallet in over 800 days (mostly bc there’s garbage on it). I didn’t see why someone would want to buy a wallet with no worth so i passed on his offer.

Later in the day he’s now offering some kind of scheme where he sends me crypto but then wants me to send half back to him. He would then send me more and I would send half back.

What’s the end game of this guy? I assume if I send back what he wants, it gives him some kind of access to my wallet?

Edit: I meant to click “advice” For the flair but somehow clicked “staking”. Sorry for confusion