1. Reduce screen brightness: Reducing the brightness of the iPhone's display can have a big impact on its battery life. To do this, go to Settings > Display & Brightness and turn down the brightness slider.
2. Turn off background app refresh: Many apps can use data in the background and drain your battery. To prevent this, open Settings > General > Background App Refresh and turn off Background App Refresh for any apps you don't need constantly running in the background.
3. Turn off location services: Location services can be a big battery drain, but they don't have to be. To turn off location services, go to Settings > Privacy > Location Services and turn off the setting for any apps you don't want tracking your location.
4. Use Low Power Mode: Low Power Mode is a great way to extend your battery life. To turn it on, go to Settings > Battery and toggle the switch for Low Power Mode.
5. Replace the battery: If all else fails, you may need to have your battery replaced by a professional iPhone repair shop.