Tracking stolen iPhone 12 Pro Max using serial number

You cannot track your iPhone using its serial number. If Find My was enabled on the phone,, you can try to track the phone using that. If you do see a location, you could give it to the police, but it would be very unwise to go there in person to confront criminals yourself. You might lose a lot more than a phone.

The pragmatic reality is that if your phone was indeed stolen (vice simply misplaced) …

… you’re not getting it back and FindMy is largely an irrelevant and inappropriate tool for you.

Any data on your phone is VERY well-protected by your passcode.

So … proceed accordingly as outlined here:

If your iPhone or iPad was stolen - Apple Support

If the IMEI is needed for any police reports or insurance claims, you can obtain it from your carrier, from the device’s original packaging, or from the “Devices” tab at https://account.apple.com/.

Finally, once you obtain a replacement device:

Restore your iPhone, iPad, or iPod touch from a backup - Apple Support