Just press and hold the buttons on both sides. That you can do this surreptitiously is very much by design. This is important because it means you can easily hard-lock your iPhone without even looking at it, or removing it from your pocket or purse.

You can’t use Face ID or Touch ID again until the passcode has been entered. The important thing to note is that you don’t have to do anything on this screen to hard-lock your device - once you’ve gotten to this screen, the device is already hard-locked and will require the passcode to unlock. 2 This takes you to the screen where you see a slider to power down the device, and on iPhones, where you can initiate an Emergency SOS call or view the device owner’s Medical ID (if they have one). 1 You’ll know when you’ve pressed the buttons long enough because there’s haptic feedback. With recent iPhones and iPads, you enter this mode the same way that you turn off the device: by pressing and holding the power button and either of the volume buttons for about two seconds.

When you hard-lock your iPhone or iPad, it enters a mode that requires the device passcode to unlock.

Here are two essential things everyone should know. The problem is this: if you use Face ID or Touch ID on your device (and you almost certainly should), what happens if law enforcement (or anyone else for that matter) takes your device and physically forces you to unlock it biometrically? There is some legal precedent supporting the notion that police can force you to do this, but can’t force you to provide them with a passcode or passphrase. Even if you’re not the sort of person who typically shares iPhone tips with your friends and relatives, this is one that you should spread the word about. here and here - but because I consider it one of the single most important things to know about iOS, I should write about it more often. How to Temporarily Disable Face ID or Touch ID, and Require a Passcode to Unlock Your iPhone or iPad Monday, 27 June 2022

Iphone passcode reset requirement