You can set the Power button to call Google Assistant when you press & hold it.
If you enable this gesture:
- To see Power menu options (Emergency, Lockdown, Power off, and Restart), press Volume up and Power buttons at the same time.
- You can't use Volume up and Power buttons to silence your phone.
Set it up
- Go to Settings > System > Gestures.
- Touch Press & hold power button.
- Turn Hold for Assistant on
.
Use it
Press & hold the Power button, then speak your command.