I got the same wear os 3 emulator issue that the ambient mode for compose wear always-on example is not triggered automatically.
It appears to me that it is an known issue (
https://issuetracker.google.com/issues/234054917)
In addition to the change “ambient temperature” option described by
@florent, the following approach works for me:
1. With ac “off” first:
adb emu power ac off
2. Use the
Palm
button on the menu of the wear emulator 30, the ambient mode can be trigged manually
3. with
2
button on the menu of wear emulator, app goes back to active mode.