I'd say that feeding the chicks shouldn't be that different from feeding the grown birds--though obviously, you would want to make sure that the things are in small enough pieces, or soft enough, that they are able to swallow or tear of pieces. And bearing in mind that young growing birds might benefit from a little touch extra protein-rich foodstuff, and don't need as much calcium as layers (although if you have a flock of mixed ages it's easy to just give calcium free choice and that solves any of those issues quite nicely).
IMO starting the chicks as young as possible on a diverse, interesting diet will give them a healthy start, but also make them more amenable to trying new things you may want to feed them in the future. It's a good opportunity to "train" them to eat the things you will be feeding them later on.
For example, in the Korean Natural Farming method, they start the chicks out immediately on a diet of brown rice and bamboo leaves, so that their digestive tracts become better adapted to a high-fiber natural diet, and then after that they feed them the same kind of mix the adults get, just chopped up much smaller.