Track lost phone
How do you track the last location on a device that has powered off?
iPhone 11
This support article has a list of things to do if your iPhone, iPad, or iPod touch is lost or stolen. --> If your iPhone, iPad, or iPod touch is lost or stolen - Apple Support
You can't track it if it is turned off.
If Find My iPhone is offline or not working, read this Apple Support article to get help; e.g., when you don't see your device listed, or you see an unexpected device or an alert that says your device is offline. --> If Find My is offline or not working - Apple Support