Samsung
Show or Hide the Lockdown Button in the Power Menu auf Samsung
The Lockdown button exists because biometric unlock methods on Samsung phones, such as Face Detection, Smart Lock and the fingerprint sensor, can be tricked or bypassed in certain situations. One UI added a dedicated switch that lets you force a PIN, pattern or password entry straight from the power menu, disabling every biometric shortcut for that single unlock.
The toggle lives inside the secure lock settings, one level below your normal lock screen options:
Settings ➔ Lock screen ➔ Secure lock settings ➔ enter your current PIN, pattern or password ➔ toggle Show Lockdown option.
Once enabled, holding the power button (or the volume up plus power combo, depending on your device) adds an extra Lockdown entry next to Power off and Restart. Tapping it locks the phone and mutes biometric and Smart Lock methods until you type your credentials again.
Hiding the button does not delete your PIN or pattern, it only removes the shortcut from the power menu. If you rarely hand your phone to other people or trust your biometrics, leaving it hidden keeps the power menu shorter. If you cross borders, attend events, or lend your device temporarily, keeping it visible gives you a one-tap way to shut off biometric access without touching any other setting.