iPhone 11 suddenly overheating and draining battery after updating to iOS 16.5.1?

Some activities such as charging or a lot of computational activity (e.g., video), generate heat. Some warmth is to be anticipated.* Read this article about keeping your iPhone, iPad, or iPod touch within acceptable operating temperatures - If your iPhone or iPad gets too hot or too cold - Apple Support

Changes in software such as upgrades may introduce new features which may add to power drain and heat generation. Check Settings > Battery to see if there are apps running that use a lot of power. If there are, decide if you need them running all the time or can turn off a service when an app is in the background. Read this support article to learn about the battery health feature —> iPhone Battery and Performance - Apple Support

If you think there is a problem with a device, have Apple inspect it. Go to this page to find your nearest Apple Authorized Service Provider (AASP) or Apple Authorized Distributor (AAD) --> Find Locations

How to make a Genius Bar appointment

1. Go to Genius Bar Reservation and Apple Support Options - Apple

2. Go to "Get hardware help".

3. Select your hardware and continue selecting options requiring replacing parts until you see "Bring in for Repair"

4. Sign in with your Apple ID

*"Your iPhone might get slightly warmer while it charges." - from: How to use your MagSafe Battery Pack - Apple Support

Hello HDB0708!

Also, please make sure you are fully updated to iOS 16.6.

I hope this is helpful. Good Luck!