If your iPhone was set up with your Apple ID, and you had Find My enabled on the iPhone, you may be able to trace the location of the iPhone using Find My. You can also try marking it as Lost. Without a SIM or eSIM, the phone will not be learning of a Lost marking via cellular Internet, but there might be a chance of it learning of the lock via WiFi.
You can use Find My on one of your other Apple devices, connected to the same Apple ID, or log into the iCloud Web interface ( https://www.icloud.com/ ).
NOTE: If you think the phone was stolen, it probably would not be a good idea to travel to any location you may see, in person, to confront the criminals.
If the phone was stolen – or if it was lost, and found by dishonest people – the crooks may contact you, saying that they are from Apple, and wanting to reunite you with your lost phone. Apple will not contact you regarding lost or stolen iPhones. What such crooks are really after is for you to
- Give them your Apple ID, Apple ID password, and passcode information, and/or
- Remove your phone from the list of devices associated with your Apple ID
so that they can bypass Activation Lock, access your personal data, make the phone valuable to themselves (and their fences and their fences' customers), or rip you off in other ways.
Do not bite.