Find Your Lost iPhone 8, Even With a Dead Battery
With Find My iPhone turned on you can track down a lost iPhone. You need to set it up before you lose your iPhone and you need to make sure you turn on a relatively new feature that makes your phone send it's location right before the battery dies.
Go to Settings -> Tap on your name at the top -> iCloud -> Find My iPhone.
Make sure you have Find My iPhone turned on and that you have Send Last Location Turned on.
With these turned on, you can use the Find My iPhone app on another device to track your iPhone, sound an alert or even wipe your iPhone if it is completely lost.