Instead of tapping out your PIN code on the way-too-small number pad, here’s how you can use your iPhone to unlock your watch.

In order to secure your Apple Watch, Apple asks you to enter a PIN code on initial setup. The watch then knows each time you’ve taken it off your wrist, and requires you to enter your PIN on a tiny number pad to unlock it.
…
Read full post here:
https://www.cnet.com/how-to/how-to-unlock-your-apple-watch-using-your-iphone/