WhatsApp is developing a new feature to make it easier for users to respond to messages. Double-tapping on a message will make it possible to send a "thumbs-up" emoji directly in response.
Currently, the feature is not yet available, but is expected to be released in a future update to the app. In the future, it should be possible to edit messages after they have been sent, but only within the period of 15 minutes. Numerous other functions are in development, including the ability to create stickers.