I would return the phone to walmart and get a new one.

Sounds like they must’ve sold you a used phone.

The problem is I don’t want to return the phone. The phone is part of the deal of upgrading my plan. If I return the phone. There’s no value to upgrade my plan. 

Return it and get a new one/exchange it, that way you’ll still maintain the deal, but hopefully get a brand new phone this time.

I have tried. Walmart has sold out all their iPhone 11. That’s how I get stuck

Unfortunately because you bought the phone from Walmart, it needs to be returned/exchanged through them.

The only options at this point then would be to return it and then buy the phone elsewhere or take the phone as is.