I'm on a Pixel 6 and trying to get adaptive charging without an alarm to work, but I don't know how it would work. I noticed that without setting an alarm and plugging in my phone, I don't get the notification about adaptive charging that I normally get.
Does that mean this feature is not ready for me yet (as in not rolled out or it can't detect my sleep pattern), or does this work without the notification?
It might not be rolled out to you yet. If it's working you can see it on the Always-on Display ("adaptive charging - fully charged at [time]" or something like that)
It might help to set an alarm time but turn off the alarm. Then it should be fully charged at the time you've set for the (unused) alarm.