My daughter received an Apple Watch Series 4 as a gift I have no contact with previous owner how can I pair with her iPhone

There’s nothing you can do if it’s Activation Locked. The previous owner must unpair the watch and remove Activation Lock by entering their Apple ID password, so you can use the watch. What to do before you sell, give away, or trade in your Apple Watch, or buy one from someone else - Apple Support 

rosabella276 Said:

"My daughter received an Apple Watch Series 4 as a gift I have no contact with previous owner how can I pair with her iPhone"

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Get Logged Out:

The previous owner needs to sign themselves out of it. this is an anti-theft measure. So, you'd stuck, if you cannot log out.