Is it possible for someone to sell me a used iphone but its actually old hardware in new shell, so it looks like ax X but is not?

Is it possible for someone to sell me a used iphone but its actually old hardware in new shell, so it looks like ax X but is not?

Added (1). sorry for some typos. Anyways, I ask because I'm using the app offer up to buy a iphone x, and i just want to know if i should be wary and when i inspect the phone if there's a way to check if its been tampered with so it has older hardware.

If you buy from a reputable authorized seller, you should have nothing to worry about.

No. The internals of iPhones differ enough that it would be next to impossible to do so. The closest you'd get to that is the iPhone SE which is basically a 6s in a 5s' body.

No.

But - there are look-alikes or clones, Chinese fakes that sell for $100
Be very! Careful if is not one of those.

They are actually a cheap android phone with modified icons and a black notch graphic in the screen background image, not in the phone!

More info here