Apple Watch Series 3 connect to iPhone 15?

Yes you can use a series 3 watch with iPhone 15. This link shows the steps to get your watch to pair with your new phone Unpair and erase Apple Watch - Apple Support

I have read (from google searches) that compatible watches with iPhone 15 (which comes with iOS 17) include Apple Watch Series 4, 5, SE, 6, 7, 8, 9, and Ultra. Watches such as Apple Watch Series 3, Series 2, and the original Apple Watch are not compatible.

However, see the replies to:

Can i use my series 3 watch with an ios17… - Apple Community

So, there seems to be some discrepancy.