Complications are one of the ways you can customize your Apple Watch face. They are small widgets that display information from apps on your watch face. For example, you can see the date, weather, battery life, activity rings, and more. You can also add complications from third-party apps that you have installed on your watch
To use complications on your Apple Watch, you need to choose a watch face that supports them. Not all watch faces have complications, and some have more than others. You can see which watch faces have complications by looking for small boxes or circles on them. You can add or change complications on your Apple Watch using your iPhone or your watch.
Here are the steps for each method:
Using your iPhone: Open the Watch app on your iPhone and tap My Watch. Tap a watch face under My Faces or tap Face Gallery to choose a new one. Scroll down to the Complications section and tap a location. Then scroll through the list of available complications and tap the one you want to add. You can also reorder or remove complications by tapping Edit in the upper-right corner.
Using your watch: Press the Digital Crown to go to the watch face on your Apple Watch. Press firmly on the watch face to enter customization mode. Swipe left until you reach the Complications screen. Tap a location and use the Digital Crown or your finger to scroll through the list of available complications. Tap a complication to add it. Press the Digital Crown again to save your changes.
You can also use Siri to add complications to your watch face. Just say something like “Hey Siri, add Weather to my watch face” or “Hey Siri, change the middle complication to Calendar.
I hope this helps you use complications on your Apple Watch.