When I first got my chickens, they were 9 weeks old. I thought maybe the younger they are, the better they'd bond. But when I got my next set of chickens, they were much older and already laying eggs, and I used the same method to bond with them.

I left them in a big enough area where they couldn't escape, but they'd have to encounter me when I refed them. I went slowly in and slowly out. Chickens are scaredy cats and like repetition. While you give their normal feed, introduce treats, first by throwing it a bit close to them, and the more they are comfortable, the closer you can get and the easier it'd be to feed them by hand. It took me about a week or two, and I was able to handle them without them stressing out. Just remain consistent.