There’s no much difference between the usual colored status we see on Facebook app and Messenger. It’s really a nice feature, and now it’s coming to Whatsapp.
Though not all currently use the Status feature, Perhaps WhatsApp hope it will convince people to start using the status feature.
Go to the Status tab and look for the floating pencil button on the bottom right.
Even as a Beta tester, after updating to the latest Whatsapp version, you might not see the feature, as it’s not yet visible to all Beta testers. It could be a server side switch or it might require you clear app data before it can show up.
If you are a beta tester, you can update your WhatsApp to the latest version on Playstore.