Pair a watch that was given to me, don’t have passcode or email it was set up with

Your best bet is to bring it to an Apple Store and they’ll do the necessary verifications to make sure that your device was not stolen. If you meet their requirements, they’ll be able to unlock it.

The person that you bought this watch from needs to follow all the steps in this link;

Remove the Activation Lock so that the buyer can use it.

If they can't or won't then get your money back or recycle the watch and put it down to experience.