My youngest is 9 so far....but I only have 2 tribes going and they are each on their first chief.

Does the game assign a villager to be chief before they try on the robe?

In my first game, the first person I sent to the robe became the chief. (and that was before I even knew what was supposed to happen)

In my second game I had to go thru all of my adults and two children before I found someone who fit the robe. (the 9 year old)