According to WABetainfo, a website that tracks WhatsApp in Beta, the feature will be very helpful specifically for Pixel 4 users as the device comes without a fingerprint sensor and only supports facial recognition.
Once the feature rolls out, the "fingerprint lock" settings will be renamed to the more general "biometric lock".
The settings are likely to be based on Android's BiometricPrompt API, which allows apps to use biometric unlock for authentication.
Face unlocking has already been on iOS for some time now, which makes sense given the iPhone X first introduced FaceID back in 2017.
Whatsapp is also bringing a feature like Skype and Zoom where one can join the ongoing calls even if you have missed. This means when a user is busy and can't join the video or voice call can join them later when the call is still ongoing.
WhatsApp has enabled multiple features like 'Always Mute option', a new Storage Usage UI along with accompanying tools as well as new Media Guidelines to its Android beta user base.