About battery life

There is no means to improve battery health, there are only means to slow the inevitable and inherent degradation and decline into failure and replacement.

For what Apple recommends for maintaining rechargeable batteries, see ➡️ iPhone Battery and Performance - Apple Support

You can try this: https://www.apple.com/batteries/maximizing-performance/

Also, you can try some of my tips.

you can lower screen brightness or turn on auto brightness. To lower screen brightness, swipe down from the top right of your iPhone screen too open the control center, and find the brightness bar, lower that until you can still see comfortably, but it isn’t too high.

enable dark mode. Settings- display and brightness- turn dark mode on. (And I think it looks better too.)

enable optimized battery charging. To do so, Settings > Battery > Battery Health > Optimized Battery Charging.

turn Bluetooth off.open settings, press Bluetooth, and turn that off.

force quit apps. Swipe up from the bottom of the screen, and pause in the middle. This will bring you to the app switcher, which is a list of all the apps you have open. Swipe on close them.

Enable low power mode.

To do that, open settings, press battery, and turn on low power mode.

finally, set auto lock to 2 minutes. To do this, go to settings, display and brightness, and set auto lock to 2 minutes.

all of these tips should help to maximize battery life. And slow down your battery health decrease.