Now the introduction is plausible. First you need the latest WhatsApp version. These can be found here. After the update, tap "Settings", then select "Account". The fingerprint lock is then hidden under "Privacy".
Activate "Unlock with fingerprint" and confirm your fingerprint. Users can set whether they should enter the lock after one minute or 30 minutes.
If the fingerprint lock is enabled, users must first unlock the messenger and then read the message. Incoming WhatsApp calls or video calls can still be accepted without unlocking.
By the way: If the update is not available for you, you can still use fingerprint. All you need is an additional app. With the App Lock for Android tool, you can easily protect WhatsApp and other applications on your smartphone with a PIN lock, pattern, or fingerprint.