In networking in general, you have client side with a function to connect, and functions send/receive to exchange messages.
It also means that you need to make a server that handles the connexion between the clients and is the source that receive the messages from the client and then broadcast it, as well as deal with the game's logic.
The idea behind webRTC is that this server is "the webRTC service", a sort of "cloud" you don't touch upon, leaving you with nothing but the connect/send/receive to handle.
You have little to no access to the server which only purpose is to deal with connecting clients (browsers) one to another and exchange messages between them.
So yes, in the end, even with webRTC, a "gameplay" server will be required to be coded by the game maker, my mistake.