For quite some time now WhatsApp has been testing a feature that will allow you to set an “expiration date” for the messages you send, or “self destruct” if you like to think about this in a more “James Bond” way. This feature is useful for people who want to send confidential messages on WhatsApp without risking others seeing the messages.
The feature was initially named Disappearing Messages but now, after some adjustments have been made, the feature will be called Delete Messages.
Included in the code of the latest beta version of the WhatsApp for Android app, the option allows you to send messages that will disappear after one hour, one day, one week, one month or one year.
When the option is activated in the Contact Info or Group Settings section ( just by administrators of the group ), the Delete Messages feature will automatically delete messages past their expiration date.
This new feature is also compatible with the Dark Theme but it is not available at the moment for all users however recent improvements that were made suggests that WhatsApp is ready to implement it very soon.