Select time duration for Face ID or Touch ID to be required.Toggle Require Face ID / Require Touch ID on.Click on the Settings tab in the bottom right of the screen.To lock WhatsApp on your iPhone so your face or fingerprint are required to see your WhatsApp chats even if your iPhone is already unlocked, follow these steps: These apps include banking apps, various retail apps like Klarna, and you can set WhatsApp to as well. Several apps request Face ID or Touch ID authentication to grant access, even when your device is already unlocked. (Pocket-lint) - Apple's Face ID and Touch ID can be used for a number of purposes, not just unlocking your iPhone or authorising an Apple Pay payment.