Can't connect Apple Watch to my iPhone
I have used Apple Watch and I want to connect with my phone but want old owner Apple ID and password and I don’t have that what should I do
[Re-Titled by Moderator]
Return the watch to the seller and get your money back. You cannot set it up with your iPhone as the seller did not properly setup the watch for resale. Please refer to What to do before you sell, give away, or trade in your Apple Watch, or buy one from someone else - Apple Support
Until the old owner does these steps, unfortunately you simply have a brick.
Next time, if you want to buy a used Apple product I would suggest visiting Apple's refurbished store. You can find it at Certified Refurbished Products - Apple