Mac os Sequoia 15.7.2 does not sync with Apple Watch iOS 18

Follow the previous good advise

You cannot directly sync an Apple Watch to a computer because it requires an iPhone to be set up and managed.

However, you can use your Apple Watch to unlock your Mac as outlined by @ 6x6 👍, which is a form of "syncing" that simplifies logging in.

For other types of syncing, such as photos or fitness data, the process is indirect: first sync the data from your computer to your iPhone, and then the iPhone will automatically sync it to your Apple Watch. 

If your Apple Watch is not unlocking your Mac:

1. Turn off "Watch Unlock" on Mac
2. Pick up your iPhone and open the Watch App
3. Unpair your Apple Watch from the iPhone
4. Pair the Apple Watch to your iPhone
5. Turn on "Watch Unlock" on Mac
6. Shut down the Mac completely and turn back on