Find my phone

Hi there

If your device says offline in Find My, most likely it isnnot connected to the internet or has been turned off

Locate a device in Find My iPhone on iCloud.com - Apple Support (PH)

• "If the device can’t be located: You see Offline under the device’s name. The last known location is displayed for up to 24 hours. Select “Notify me when found” to get an email when it’s located again."

You will just have to wait until it gets online to see the current location

Find My is the only way that you can track or locate a lost or missing device. There is no other Apple service that can find, track, or otherwise flag your device for you. 

You can check this article for more help

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

What might “off[]line” mean?

Perhaps you can telephone it and hear it ring.

Perhaps you can spot it using your eyes.