Click on this link for general information about what to do "If your iPhone, iPad, or iPod touch is lost or stolen" --> https://support.apple.com/HT201472
- The Find My service is the only recovery feature Apple offers. It MUST be set up before the device is lost. If you did not do that it is too late to do it now and there is no other feature Apple offers that can help you find it.
Click on this link to read how to "Use the Find My app to locate a missing device or item" --> https://support.apple.com/HT210515
The chances of locating a device depend upon which features you selected in:
Set up Find My on your iPhone, Mac, and other devices - https://support.apple.com/HT210400#enablefindmy
Thieves would have to know your friend's APple ID and password in order to be able to disable the Find My feature.