Stolen phone

If you didn't turn on Find My [device] before your device was lost or stolen, it can't be used to locate your device. Best actions would be; Change your Apple ID password. Change the passwords for other internet accounts on your device. This can include email accounts, Facebook, or Twitter etc...

Neither we, just users like you, nor Apple can get involved in lost or stolen iPhones.

We can only offer you this support article which contains the steps you can perform (with or without Find My [device] enabled:--> If your iPhone, iPad, or iPod touch is lost or stolen - Apple Support

Regards and best of luck.

Giulio