Yes, I had plans for that Control Ring well ahead of purchasing my Canon EOS RP 3 weeks ago.
I like as many control wheels as I can on a camera — which is why, for about 6-months, I was totally convinced that the Fuji X-T2 was going to be my dream camera. Now, with this control ring on the lens (or on the lens adapter) I do have a 3-wheel camera.
As I show in the top diagram I assigned ISO control to that ring. Exposure compensation (EV), automatically, is on the rear wheel and since I shoot in ‘Aperture Priority’ mode most of the time, aperture setting is on the front wheel. Works great for I — though I am still getting used to finding the right — of the three rings — on my 24-105mm lens.
But, this is definitely worth keeping in mind. Really makes the Canon EOS RP a joy to use.
Search ‘EOS RP’.