Next … re: your stolen iPhone:
First: Remain calm. Do NOT panic.
Your phone and the personal data it contains is VERY securely protected by it’s passcode.
Thieves prey on the bad decisions we are more likely to make when anxious.
Next = = =
Start working thru this checklist:
If your iPhone, iPad, or iPod touch is lost or stolen - Apple Support
Place it in “Lost Mode” with an on-screen message of how to contact you for a return.
Caution: Don’t reveal personal info in the screen message; it will be viewable by ANYONE in possession of the device. Just stick to the bare minimum info needed to reach you.
Finally = = =
WARNING: Going forward - in the coming minutes, days, weeks, or even months - EXPECT messages from the thieves, usually claiming to be Apple (or sometimes the police) which attempt to phish your personal info so as to be able to break into your phone and/or AppleID.
These are criminal attempts; although they can appear VERY “official,” polished, and convincing.
Disclose NOTHING and do NOT follow any links they might contain.
Absolutely DO NOT EVER provide ANY of your Apple credentials (AppleID, AppleID Password, or Device Passcode) in response to these messages.
They are NOT from Apple or from anyone else legitimate.