I had the same thing happen on my S7 and my Note 7. In both instances I restored either from a backup or the smart switch. With my Note 7 I would take it off the charger at 9 pm before going to work and would be at 30% by around 3 am. Not great. So despite the time it took to setup the phone I decided to do a hard reset, as I did with my S7. Now by 7 am, depending on use, I'm at 30-40%. That's with using an audio book player on for about 3-4 hours. Still tweaking it a bit. But it's gotten better.
I'm going to try package disabled and see where I get after that. Hopefully it should get better.
FYI.... I also use dark themes on the phone and any apps if available. I also keep the screen at about 50% brightness which is fine for me since the nits on this phone are crazy bright.