Assuming that you enabled Find My on the phone, it will not show up on a map if the battery has run down or the phone does not have a good Internet connection at its current location.
Unfortunately, not much that you can do about either of these things other than keep checking to see if the phone shows up on a map, which would indicate that Lost Mode has been enabled on the phone.
If your iPhone, iPad, or iPod touch is lost or stolen - Apple Support
Scams are everywhere, so if you see a message or email from "Apple", "Apple Service", or the "Police" indicating that your phone has been found.....and you just need to provide a bit more information so the phone can be returned to you......ignore and delete the message, which is trying to trick you into providing info like your Apple ID and Password so the bad guys can get into your phone. Apple will never send a message like this, so you know the message is not real.