Since the features is expected to rolled out first for iOS platform, but the latest release (v20.16.80) for android have the video call option. Video calling features is not a public rolled-out, not all the features available as of now.
The UI design of for the latest release of Whatsapp Apk remain same as earlier, but when a users tap on the call option, there it gives the two option as Audio Call or Video Call.
The features is not available till yet and there is no updates on the Playstore for the following. Right now we can use the video calling features, but stay tuned for more update from Facebook.
Here we are providing android version of the Whatsapp which have the video calling features, (Download from Here). This version is also compatible with Android 6.0 Marshmallow version.