At the shelter, when we let two dogs out in the play yard together for the first time there is always posturing. They generally work it out with little interference from us. At time, when we do have to intervene, we never use leashes. A dog acts very differently when on a leash.
We rarely have problems beyond that, they just seem to work it out. Too bad humans aren’t more like dogs. That is why I have always preferred the company of dogs over humans.