Apple Watch pairing with iPhone 7

Apple does not allow OS or iOS downgrades. According to the link below, Apple Watch Series 4 (GPS + Cellular) requires an iPhone 6 or later with iOS 12 or later. What is the version of your iPhone 7’s iOS?

Apple Watch Series 4 - Technical Specifications

Apple may have changed the requirements. Best if you contact Apple Support directly. Tap Support at the bottom, left of the screen.

I have same problem. My experience is that during pairing, the process stops, and on the watch I get the message that the watch won't pair with older than iphone 8.

That must be an old watch model. We - other Apple users - here, do not know how to work around any Apple hardware requirements other than to recommend you purchase devices that are compatible. Sorry. You may want to contact Apple Support, as I suggested above. They would have the final word on what is possible.