So you know, Im not trying to brag about my battery compared to yours. Just letting you know it is possible to get great life out of this phone, just gotta figure out whats causing yours to go nuts. I turn alot of stuff off because I dont use it so I'll give you an idea of my settings and see how they compare to yours. Remember, I dont use the stuff I turn off so some of these may not suit your needs. These are the settings that should make the most difference.
Display:
I use AMOLED cinema mode for screen mode, auto brightness, timeout after 30 seconds, smart stay off, always on display on only at night normally while on the charger, touch key light 6 seconds, keep screen turned off toggle off, screensaver off.
Advanced Features:
I turned off all the sensor related gestures in the adavnced features tab. pop up view, smart capture, palm to swipe etc etc. I dont like any of them.
Privacy and Safety:
I only use location when I need it but even with it on I still get over 6 1/2 hours screen on time. Report diagnostics off
Google:
Nearby off, search & now > voice> "ok google" detection from the google app and from any screen toggles on. Trusted voice off.
NFC is also off because I use Samsung pay instead of Android pay. Im not sure how much NFC affects the battery.