Hey everyone just a quick question can i pair an apple watch series 3 with an iphone 7 thanks in advance.

MacTracker says the maximum OS for Apple Watch Series 3 is the latest version of watchOS 8.

Apple's user guide for watchOS 8 says that "To use your Apple Watch series 3 or later with watchOS, you'll need to pair your Apple Watch with an iPhone 6s or later with iOS 15 or later." (The Technical Specifications claim that you need the latest version of iOS, but they were written before iOS 15 came out.)

Set up and pair your Apple Watch with iPhone - Apple Support

Apple Watch Series 3 - Technical Specifications

Multiple sources indicate that you can upgrade iOS on the iPhone 7 as far as iOS 15.

So I think the answer is Yes.

Select the appropriate watchOS from the dropdown menu in this guide --> Set up and pair your Apple Watch with iPhone – Apple Support (UK)