iCloud

Please first look at this - If your iPhone, iPad or iPod touch is lost or stolen – Apple Support

You can erase the phone in that process.

Tracking lost or stolen phones

The 'Find My' tracking is to help you discover if you left your phone in the office or the restaurant. Lost or Stolen phones are rarely ever seen again. If you found the thief you probably would not like the experience.

Risk mitigation

Get your provider to 

Cancel your SIM.

Send you a replacement SIM on same number.

You can then put the SIM in another phone to get the codes you will need.

Phishing warning

Unless you had a PIN set on the SIM the thief or finder now know your number so don’t respond to texts to sign into your account!

Resign to the fact that if you had a passcode set then  your data is safe but you will never see the phone again 

Your data is safe. They just to sell the phone as parts, of with your help as an unlocked phone.

You are in more danger of being

scammed by text to reveal your AppleID password if you get a new SIM in the same number (which you may need to get 2 factor auth codes)