Some malicious apps might force the processor to work indefinitely until it burns out. And it's at this point that overheating and battery draining problems arise. To figure out which of your apps is misbehaving up, look at your iPhone 7 Plus's battery usage and see which app consumes the most power. This is how you get to this menu:

1. From the Home screen, select Settings.
2. The battery should be tapped.
3. Wait for the Battery Usage information to appear.
4. Show Detailed Usage by tapping the button. This will reveal a breakdown of front and background power consumption.
5. Tap the Last 7 Days tab to get a more comprehensive picture of power consumption over time.
6. The battery usage in iOS 12 may be examined in the Settings-> Battery-> Show Activity menu. Tap Battery Use to see usage data in percentages. Tap Last 10 Days to see your iPhone's power use over time.