2 Use the Low Power Mode
Several editions of iOS ago, a new feature came to iPhones called Low Power Mode. You can head to Settings on your iPhone, look at Battery, and find an option up on the top to turn on Low Power Mode. Toggle it on.
This mode does several handy things. Low Power Mode shuts down some unnecessary draws on battery power (including a few features we will talk about later), like automatic downloads and certain visual effects. Apple claims that this can help add at least three more hours onto your battery life, and tests seem to confirm this is true.
FYI: There’s a low power mode for the Apple Watch too, called the Power Reserve mode. This shuts down everything on your Watch except for the clock face. This is useful if you need to conserve power but still want to keep on using your Apple Watch and booting back up when necessary.