Use passcode to power off

You don’t.

it has never been a feature of any iPhone.

Emdadul_Haque wrote:

Password or passcode all are ok

but anyone unauthorized person get my phone and he make power off then I lost my phone so I want , to set passcode before power off

When you power off the iPhone, do you see this message? This has been available on phones purchased for many years now. You can still use Find My, when your phone is shut off, so that does not mean your phone is lost. There is not an option to require Face ID/Passcode to shut off your phone.

There is no such option. This has been brought up many many times and is not a good idea. For one, if your phone locked up and you needed to reboot or shutdown that would be impossible to do if you had to input a password.

but anyone unauthorized person get my phone and he make power off then I lost my phone so I want , to set passcode before power off.

Any thief already knows that they can place your phone in a special type of bag that will not allow the phone to either send or receive a signal. So, the thief does not need to power off the phone to prevent you from trying to locate it using Find My.

Requiring a code for power off would also create nightmares for users and service shops who are trying to troubleshoot a problem with the phone.

Apple will never have this "option".

Very doubtful.

But if they somehow set this, then ask them how they did it.

My friend iPhone already set this option

I don't think so. Why is it that your friend cannot tell you or show you how to do what they claim that they have done?