How to find a lost iPhone, iPad or Mac – even if it’s offline

The new Find My application is available in iOS 13 and macOS Catalina and integrates the “Find My Friends” app. This means you can not only track all of your devices, but also any friends with whom who share location. One of the marquee features of the Find My app is support for locating devices even when they are offline. This means if you lose your Apple device, you’ll still be able to locate it even if it’s offline.

https://9to5mac.com/2019/09/01/find-my-lost-iphone-offline/