I've found like three things to turn off. Finding one was easy. But to root around looking for things to turn off is not hard but time consuming & elaborate.
Here's the eight step process to turn off Voice assistant and that seems like just one measure. https://www.tomsguide.com/how-to/how-to-stop-your-android-ph...
Battery drain hasnt been night & day different since starting to disable stuff. It's just unclear what is and isn't actually disabled.
Also try resetting app settings. if something is draining in the background, that could help.