I think it depends on your dogs. With mine, who are 10, 3 and 1, all males with the 1 yr old entire, it is more clear cut because of the age gap, but as JG says it can vary depending on the situation. A friend of mine has 2 neutered males, one is 3, the other is nearly 2. When it comes to toys the eldest is clearly in charge but bring food into the situation and the youngest is very definitely the boss!
Also I think the sexes make a difference. With domestic dogs it is
usually the bitch who is in charge with the next eldest male following her. In larger packs there will often be an obvious 'omega' at the bottom. Again this varies from pack to pack but it is not
always clear who is in charge, although the dogs usually know!
Within a dog walking group, by which I assume you mean literally a group of dogs and handlers who all go walking together, things will change again. The pack's alpha males and females will be in control of their subordinates and it is down to them (and handlers of course!) to decide who plays with whom, etc. The alphas themselves will not usually confront each other unless they are particularly fiesty or a problem arises they can see no other way out of. Sometimes you can get a very strong alpha bitch who will take charge over the entire pack but this is normally done by strength of character. In other words, dogs are not stupid, they don't want to get injured unnecessarily!
I must emphasize this can be drastically different from one pack to another and is just a theory on how packs work. There will always be dogs who are different and don't behave as expected so please don't go thinking your dog is weird because it doesn't behave like this! ;-) Personally I am fascinated by pack dynamics and spend hours trying to work out what different behaviours mean.
Hope that helps, or has it made it clear as mud?! :-)