The only way you can locate your iPhone is in Find My. If it shows "Offline" or "No Location" found, it's likely that the thieves have tampered with your iPhone so it cannot transmit its location. Also the odds of your stolen iPhone being recovered are slim to none.
You will probably receive some messages claiming to be from Apple or Apple Support stating that your iPhone has been located or found. Do not interact with those messages, they are a scam. The thieves are trying to get you to remove Find My off your iPhone, making it fully usable to them.
I would advise you to turn on Lost Mode, report the iPhone stolen to your carrier and local law enforcement. Also if your iPhone does happen to show up in Find My, do not try to retrieve it. This can put your safety at risk, instead tell local law enforcement.
Also please view the following article:
If your iPhone or iPad was stolen - Apple Support