Pairing new Apple Watch to iPhone without iOS 18 support

SaraZee wrote:

I phone 11 pro max

See KiltedTim's response just above yours. Your iPhone supports iOS 18. So you need to update your iPhone to iOS 18. Then you'll be able to pair your new watch to it.

If you a have a new watch running Watch OS 11, you will need an iPhone running iOS 18.

Which model of iPhone do you have?

The information in your post seems to indicate that you have an iPhone 11 Pro. That model supports iOS 18. If you have a device that can't run iOS 18, you can either return the watch for a refund or buy a phone that can run iOS 18.