Apple Watch 8 with iPhone 7 plus

Hi,

Unfortunately there isn't. Apple Watch series 8 requires the latest version of iOS (16.1), but iPhone 7 Plus won't receive any updates past iOS 15.

No, you are still required to have iOS 16. But you could use a family members iPhone that is on iOS 16 to start using your Apple Watch series 8

You could set up your Apple Watch series 8 using family setup, but this probably won't provide the full experience.

To use family setup, visit: Set up Apple Watch for a family member - Apple Support

can you help me?

Of course, what is your question?