Get hands-free help from Google Assistant

To enable Google Assistant on your Galaxy Watch 4 or Galaxy Watch 5, search for Assistant in the Play Store on your watch. Install (or update) it, then open the app to complete the setup. To toggle Hey Google detection, go to Settings > Google. To assign the Assistant to your watch's top button, tap Settings > Advanced features > Customize keys.

On the Google Pixel Watch, holding the watch's secondary hardware button (the one above the crown) launches the Google Assistant. You can also toggle Hey Google detection from Settings > Google > Assistant. Watches currently on Wear OS 3.2 (right now, that's every Wear OS 3 watch not made by Samsung or Google, which are on version 3.5) currently don't have access to Google Assistant.

On pre-Wear OS 3 watches, Google Assistant is preinstalled. Press and hold your watch's power button to talk to it. To enable or disable hotword detection on your watch, hold the power button to open Google Assistant, then scroll down to Settings. The next screen shows a toggle for Hey Google listening. If holding your watch's power button doesn't bring up Google Assistant, go to Settings > Personalization > Assistant access and turn on Press and hold power button for Assistant.

https://www.androidpolice.com/