3pcs Iphone stolten

My last 3pcs iphone was stolen. but I'd like to find the SOB who stoleit . I can't find any information on registering the serial number as stolen with Apple. Apple has a way to track serial numbers when the thief activates the stolen phone? Can someone help me with this i.e. tracking down a stolen iphone?
I see that can lock the iPhone for all carrier and put it in black list or something like this... so how can i make this...!
plz help me this is 3pcs iPhone 😟 😟 😟 😟