I bought an Arc and I want to know directly from Sonos what happens to the speaker arrangement inside the Arc when I connect the 2 One’s?

I have heard that if the surround channels are taken over by the One’s, it frees up two of the Arcs surround speakers to drive more bass response? Is that an accurate understanding of how the software sorts itself out? thanks! If not please explain what happens with the two One’s.  Thanks again!