One of the most handy features previous to Android Wear 2.0 was the ability to triple press the crown for sunlight mode for a few seconds while outdoors. Google saw fit to remove this in AW 2.0 focusing on just those watches with ambient light sensors and forgetting about the rest of us.
Thankfully a developer out there has found a way to add this back. Fair warning this will disable the long press to activate Google Assistant. If that's find with you then please proceed.
First you'll need to download and install Bubble Wear Launcher. You can either choose your watch from the drop down and install it from the web or search and find it on the Play Store on your watch. I'm not a fan of this watch face by any means, but after we set it up you won't have to continue using it.
After you install it set Bubble Cloud as your watch face and then click the settings cog underneath it. From there you can scroll down until you find "Long press button:" scroll down and select Sunlight mode. There is another option called "Press again:", and for $3.95 for premium version you can add Assistant for that shortcut. Then you won't lose the ability to launch Assistant from the crown.
Now when you long press the crown you will get maximum brightness for your screen for a few seconds instead of Google Assistant. Even better you can change your watch face and this setting will remain active. This is so helpful when outdoors and helps you save your battery while you spend most of your time indoors. Remember you can still access Assistant if you've turned on OK Google detection under personalization. Anytime the screen is lit up just say OK Google and Assistant will spring into action.