WhatsApp is developing a new feature called "Delete Messages" that will allow users to set their messages to self-destruct after a set period of time.
Messages that have been deleted automatically have been around for a long time Telegram and can be enabled in private conversations on both iOS and Android.
WhatsApp will enable automatic deletion of messages in all conversations and this feature is already available in the 2.19.348 beta for Android devices. It's called Delete Messages, and it can be activated from the Contact Information screen, but also available in groups if administrators enable it.
Messages automatically deleted in WhatsApp will come with many predefined values, namely 1 time, 1 day, 1 week, 1 month and 1 year. Support for predefined message deletion times does not seem to have been fully set yet, but these capabilities are missing from Telegram applications.
The new feature is already at an advanced stage, as it even supports the dark mode of the application. The dark mode for WhatsApp is yet to be released publicly, so there is a chance that both new features will be released together.