Unable to track my lost iPhone 15 Pro

Requiring a Passcode or FaceID to turn off the phone would make absolutely no difference. The phone does not have to be turned on and you can test that for yourself. At this point the battery will be dead if it has not been charged, so there will be no way for it to update the location. Your only hope is that someone will charge it and the location will be updated. Location is also updated by another iPhone when it is within Bluetooth range, whether your phone is on or off.

Find your lost iPhone or iPad - Apple Support

Serial Number and IMEI number are useless for tracking the device. Thieves also use Faraday bags that do not allow any outside connection. I assume you have already Marked it as Lost in Find My and if you provided contact information, be aware that scammers will pretend to be Apple and claim your phone has been found. After giving them your Password, they can set the device up as theirs and completely wipe it.

So, somewhere atleast Apple should have give this option before turn off the phone asking for Passcode or FaceId,

If you are thinking that this will prevent the thief from turning off the phone so the phone cannot be tracked by the owner, you are wrong.

Any iPhone thief knows how to prevent the phone from either sending or receiving a signal in a few seconds. The thief does not need to power off the phone to do this. If you do not understand how a thief can do this, post back and we will explain.

also the phone can be track stills it’s turned off is just a word.

I can track my iPhone if it has been turned off. Your phone can be tracked as well if it has been powered off.....if the battery has not run down completely and there is another iPhone in close proximity to the phone.

But.....the iPhone thief knows how to prevent the phone from sending or receiving a signal.....even if the phone is on.