Is this a real Apple Watch?

it’s a fake Apple Watch. Apple Watch Control Center doesn’t look like that. The form factor is even wrong on the right side. It’s running Android which is why it can’t pair/sync to your iPhone. Sorry!

"I bought the apple watch ultra from someone..."

" I don't have the original receipt..."

You are out of luck and will never be able to use the watch. Try to get your money back or properly recycle the watch and accept your financial loss.

First clue is Apple doesn’t shrink wrap most (all?) of their products. But the big clue was the screen shot showing the app icons and Control Center. I’m sorry things didn’t workout for you, but maybe it’ll help knowing your have assisted many community members.

Only the original owner can remove activation lock. You'll need to contact them.