Lost phone
How can I locate my device if it's offline
Question marked as
Top-ranking reply
If the device is offline such as when the battery is exhausted, there’s no communications, and no request for location, etc. So no means of remotely locating the device exists. Which means looking for it the old fashioned way; looking around where it might have been lost.
Overview of the general sequence:
If your iPhone, iPad, or iPod touch is lost or stolen - Apple Support