My iPhone 16 Pro Max high battery drain

Here is Apple’s advice→If the battery in your iPhone drains too quickly - Apple Support

Any cell phone uses energy continuously, as long as it isn’t powered off. This means that if it is not connected to power for 8 hours the battery level will be lower at the end of that time. How much lower depends on what apps you have, how many notifications you have enabled (which will be delivered and processed by apps even if you force close apps-they will relaunch when a notification arrives), and, probably most important, how strong your cellular signal from the network is; your phone maintains a "conversation" with the network so your phone can be found when a call or text arrives, and low signal strength requires much more energy to do this update to the network. Thus, you should be charging your phone overnight so this nighttime usage is powered by the external source rather than the battery.

The absolute best way to get maximum use on a charge, as well as slow the decline of battery capacity long term is to enable Optimized Battery Charging (Settings/Battery/Battery Health) and charge the device overnight, every night. The battery will fast charge to 80%, then pause. During the nighttime pause the phone will use mains power instead of battery power, allowing the battery to “rest”, and thus reducing the need to charge the battery quite as often. The phone will resume charging to reach 100% when you are ready to use your phone; it will “learn” your usage pattern. If you enable iCloud Backup (Settings/[your name]/iCloud - iCloud Backup) the phone will back up overnight also, assuring that you can never lose more than the current day’s updates. Here's more information→About Optimized Battery Charging on your iPhone - Apple Support

That graph doesn’t help diagnose the issue. Please share screenshots of battery usage by app for last 24 hours and 10 days. I’m confident what we’ll see is non-Apple, third party apps consuming the majority of your battery capacity.

Any cell phone uses energy continuously, as long as it isn’t powered off. This means that if it is not connected to power for 8 hours the battery level will be lower at the end of that time. How much lower depends on what apps you have, how many notifications you have enabled (which will be delivered and processed by apps even if you force close apps-they will relaunch when a notification arrives), and, probably most important, how strong your cellular signal from the network is; your phone maintains a "conversation" with the network so your phone can be found when a call or text arrives, and low signal strength requires much more energy to do this update to the network. Thus, as Apple recommends you should be charging your phone overnight so this nighttime usage is powered by the external source rather than the battery.

You should also turn on nightly automatic backups, so in the event of disaster you won’t lose more than 1 day’s updates.