WhatsApp seems to be working on a lot of new updates recently. It is all set to introduce some additional features including Touch ID and Face ID support. The reason behind this update is to combat competition. Recently it has also added the Swipe to reply feature to its Android app.
The Touch ID and Face ID feature are said to be in the Alpha mode as of now. With this feature users will be able to lock as well as unlock WhatsApp using Face ID and Touch ID.
As of now it is doubtful as to when this feature will be available for iPhone users. It is still said to be in the testing mode.