An RCS Rich Media message is the higher of the two types every US RCS message is billed as. A message becomes Rich Media as soon as it contains any one of: a rich card or carousel, even one with no picture; an image, GIF, video, audio clip or file; or a button that shows a map, asks for the customer's location, adds a calendar event or opens a page inside Messages.
How it is billed
One flat charge per message, whatever the text length. On SimplyRCS that is $0.0150, the same inbound and outbound, plus the carrier's Rich Media surcharge at cost. A photo a customer sends is billed the same way.
File size doesn't change the price either, except on T-Mobile: its Rich Media surcharge covers a message up to 5 MB, and it adds $0.001 per MB over 5 MB, sent or received, up to the 100 MB limit. Keeping videos and images under 5 MB avoids it.
When it is worth it
Rich Media is where RCS does what SMS cannot, so it belongs where a picture, card or carousel earns its price. Conversation around it can stay in Rich messages: text with reply buttons at the text rate. How RCS billing works lists every element and its type.