According to some recent news articles it sounds like Google has released a new developer preview of Wear OS (formerly Android Wear) and is looking to help maintain better battery life in future Wear OS versions. According to The Verge, some of those ways may include:
Most apps will no longer be allowed to run in the background unless the watch is on the charger (watch faces and complications currently chosen by the user can continue to run).
Wi-Fi, Bluetooth, and cellular radios will automatically turn off when Wear OS detects that your device has been off your body for an extended amount of time.
The device will no longer automatically connect to Wi-Fi when disconnected from Bluetooth.
This is all still developer preview now, so no way of knowing when a new update will roll out to everyone with these new features; or even if these will make it into a final OS version. Now the question is, which watches will continue to receive new Wear OS version updates?