Got a new phone and can’t pair my watch. It os locked and won’t allow an option to enter passcode

Is the iPhone locked or the watch?

From where did you purchase the new device. Which iPhone is it? Unless the original owner is willing/able to go thru the steps listed in the link below, I would take it back for a refund.

What to do before you sell, give away, or trade in your iPhone or iPad - Apple Support

Here is information if it’s the watch that is locked.

What to do before you sell, give away or trade in your Apple Watch, or buy one from someone else – Apple Support

This is another good article:

The All Too Common SAD Reality of Buying … - Apple Community