What it adds
Apple's
Stolen Device Protection requires Face ID or Touch ID for certain sensitive actions when an iPhone is away from familiar locations. Some account changes also require a delay and a second biometric check. The purpose is to reduce the damage if a thief has both the phone and its passcode.
A practical example
Someone observes your passcode and steals the iPhone. With the feature enabled, knowing that passcode alone should not let the person immediately change certain Apple Account security settings away from familiar locations. You can choose an Always setting for the additional measures at home too. Apple's
feature description lists the actions and prerequisites.
The limit
The feature must be enabled before theft and needs supported iOS, biometrics and other prerequisites. It does not prevent every use of an unlocked phone or replace Find My. If the phone disappears, mark it lost and secure important accounts promptly.
