In short, yes. It depends on what they are. They can pick at soft things like melons but harder things need to be chopped for even adult chickens. Chickens will ignore things like broccoli stems, turnips, etc.. But that's because they don't have hands and teeth. If the same items are chopped into bite size pieces, they'll eat them up.
Be careful you don't give chicks too much other things unless they're high protein like yogurt, meat, fish, etc. They have little digestive systems and a lot of other things can displace the nutritional balance of prepared poultry feeds that are the result of decades research.
Lots of people do it though. I just don't because I want them to grow at the best rate possible.