I am selling my iPhone 8. I have AppleCare+ but both incidents have already been used.
All it has now is the extra 1 year warranty for defects.
It is in my name, and I was going to sell it on Swappa.
I’m afraid he may be able to look me up by calling Apple or something and charge my account or idk.
I'm afraid that your fear is not founded in reality. I'm pretty sure if you contact AppleCare, they will tell you that the AppleCare is linked to your iPhone, with no financial or private information about YOU, and someone who is NOT you will find that no previous owner information would be available through an AppleCare setup.
It's almost not even worth mentioning that it has AppleCare, if both incidents have been used, and simply adds a year warranty, as the older AppleCare did.
AppleCare+, AFAIK, does not keep "accounts", as you would pay individually for each incident, and THAT part is now useless to anyone else in any case.
(Unless you do the dumb step of forgetting to wipe the iPhone before you sell it, then make sure to leave a card in the box with your passcode, and your AppleID sign-in. That all would leave you vulnerable, but not because you have AppleCare +
)