where is the password requested for the ios

If you're talking about the passcode to unlock your iPhone, you can:

Set it going to Settings>TouchID & Passcode, and follow these steps:

Use a passcode with your iPhone, iPad, or iPod touch - Apple Support

If you forgot it:

If you forgot the passcode for your iPhone, iPad, or iPod touch, or your device is disabled - Apple Support

If you're talking about the Apple ID password, read this guide:

If you forgot your Apple ID password - Apple Support

If you're talking about a different passcode/password, please better describe your needs.

Regards

Giulio

What password?

The lock screen passcode?

Activation lock password?

Restriction/ScreenTime passcode?

Please clarify and tell us exactly what you're seeing.