battery health

Protect & Prolong life of your iPhone's Battery:

1. Put on Low Power Mode
2. Put Auto Lock On (1 min):- with low power mode it will be 30 Sec
3. Put Auto Answer Off
4. Disable Push notifications for apps you do not use often
5. Enable Auto Brightness:- Settings > General > Accessibility > Display Accommodations > Auto-Brightness [Enable]
6. Manually lower brightness from Control Center
7. If you Want to watch continuous Video. Stream it on TV or a Monitor
8. 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
9. Location services to be allowed only while using the app
10. Set your iPhone to fetch email and calendar data from internet less frequently
11. Turning off Background App Refresh 
12. Charge before it drops below 20-30%
13. Try connecting to trusted Wifi where ever available in stead of Cellular
14. Enable Airplane mode in areas with bad cellular and wifi coverage. Your phone keeps trying for reconnection with the missing / weak network. This uses lot of energy
15. Switch off Wifi & Bluetooth while in Roaming or Not in Range
16. Enable "Wifi Assist" : Settings > Cellular or Settings > Mobile Data > Wi-Fi Assist [Enable]
17. Periodically Check your Battery Health (Settings > Battery > Battery Health)

iPhone Battery and Performance

https://support.apple.com/en-in/HT208387

No, my battery life with 12.4.1 is the same as it was with 12.4. Which is excellent with both versions. If your battery life has changed it is probably coincidence. You need to troubleshoot the problem. The first step is to go to Settings/Battery and see which apps are using the most energy, then deal with them.

But... The OP did ask whole another thing...

That's the trouble with keeping a bunch of canned responses available. Frequently the one you choose is the wrong one.

To repeat what I said: The first step is to go to Settings/Battery and see which apps are using the most energy, then deal with them.