Rich Communication Services (RCS) is a communication protocol between mobile telephone carriers and between phone and carrier, aiming at replacing SMS messages with a text-message system that is richer, provides phonebook polling (for service discovery), and can transmit in-call multimedia. It is part of the broader IP Multimedia Subsystem. Google has added support for end-to-end encryption for all chats using RCS in their own app, Google Messages. End-to-end encryption is not a feature of RCS specified by GSMA.
Rich Communication is the facility of the messaging app which helps you to share unlimited messages to any one, you can share photos/videos and even audios through messages app.
You can give reaction to any message.
Note that RCS only works when both persons have RCS enabled messages app and both are connected to internet.
Google Message app is RCS enabled so I you both have Google Message then you can use it like whatsapp.
