we can  improve an iPhone’s battery life in iOS 13:

• Install the most recent version of iOS 13 software.-Install the most recent iOS 13 software update to guarantee that any bugs affecting battery life have been addressed. Navigate to Settings > General > Software Upgrade to see if an iOS 13 software update is required.
• Recognize iPhone apps Battery Life Depletion-If you still want to use the app, you should disable the Location Services (Settings > Privacy > Location Services) and Background app refresh (Settings > General > Background App Refresh) functionalities, as they can drain your battery.
• The best method to start is to turn off location services in all of your apps. You may disable location services by going to Privacy > Location Services in the Settings app.
• App Refresh in the Background is disabled.-To turn off Background App Refresh for apps like Facebook or others that don't need to be updated all the time, go to Settings > General > Background App Refresh > and turn it off.
• Make use of Dark Mode.-You can also set the dark mode on a timer. Turn on the Automatic option in Settings -> Display and Brightness.

Read More: What does Apple’s Solution for iPhone battery life in iOS 13?