iPhone 12 Pro max Draining battery so fast

iPhone 11 and later models, battery performance --> About the battery and performance of iPhone 11 and later

Try some of these options too.

1. Avoid Screen Mirroring
2. Put on Low Power Mode
3. Put Auto-Lock on (1 min):- with low power mode it will be 30 Sec
4. Put Auto Answer Off
5. Disable Push notifications for apps you do not use often
6. Keep your iPhone Facedown to prevent notifications to light up the screen
7. Enable Auto-Brightness:- Settings > General > Accessibility > Display Accommodations > Auto-Brightness [Enable]
8. Manually lower brightness from Control Center
9. If you Want to watch continuous Video. Stream it on TV or a Monitor
10. Don't force close apps; Apps which are not on frontend screen are paused by the system to save energy. Apps require more energy to re-launch. Apps which are open in the background use large memory is a myth and quitting them is counterproductive
11. Location services to be allowed only while using the app
12. Set your iPhone to fetch email and calendar data from internet less frequently
13. Turning off Background App Refresh 
14. Charge before it drops below 20-30%
15. Try connecting to trusted Wifi wherever available instead of Cellular
16. Enable Airplane mode in areas with bad cellular and wifi coverage. Your phone keeps trying for reconnection with the missing/weak network. This uses a lot of energy
17. Switch off Wifi & Bluetooth while in Roaming or Not in Range
18. Enable "Wifi Assist" : Settings > Cellular or Settings > Mobile Data > Wi-Fi Assist [Enable]
19. Periodically Check the Battery Health (Settings > Battery > Battery Health)

Mine started doing the same as well as slow performance in general ever since “upgrading” to 14.5.1. As soon as I can I’m switching back to Samsung… far superior phones! My 12 Pro Max is only two months old

Exactly. The battery drain just started on the latest releases, did not appear on any of the prior releases so all these "hints" are pretty much a waste of time as Apple needs to look in to what is causing the problem on the latest releases. All of a sudden everyday activities are now impaired due to battery issues that NEVER happened before, and I mean NEVER.

I’m not downloading anything ever again. Things just get worse in some way every new version. Just letting time pass until I’m due for a phone upgrade and then goodbye Crapple. Sorry much for giving iPhone a second chance

Shouldn’t have to reconfigure the whole phone to make it perform how it was prior to 14.5.1 upload. Apple needs to fix their software