That all depends on how you set it up. Generally speaking a lot of WebRTC is about how the connection negotiates the parameters of the delivery of the different

That all depends on how you set it up. Generally speaking a lot of WebRTC is about how the connection negotiates the parameters of the delivery of the different media, including codecs, resolution, etc. One track can be delivered over a connection in multiple different ways at once as well. If you want to know more you're probably best off going through the MDN docs about the WebRTC browser API and learning from that.