how can i find my iphone while offline??

Until it is connected to Wifi, you won't be able to locate it. The last location that it was at when it still was connected will stay on the map for 24 hours, but after that, you won't have any way to tell where it is.

It needs to be on and connected to a cellular connection or Wifi in order for the GPS to find it.

Best,

GB

Well, you can try to dial its telephone number. Perhaps you can hear the iPhone ring.

Or perhaps you can spot it with your eyes.

Otherwise, you're out of luck until it's online again.

If your iPhone, iPad, or iPod touch is lost or stolen - Apple Support