WhatsApp is slowly but surely moving towards adding a message editing feature. It appeared in the beta version of WhatsApp 2.22.22.14 for Android.
As part of testing, messenger users will be able to edit a sent message within 15 minutes. A small mark “Edited / Edited” will appear next to it.
WhatsApp has been testing message editing since 2017. Messenger again stressed that the feature is under development and there is no release date.