Hi, the other greeters have given you good info about tomato leaves. As long as your flock is getting a nutritionally sound feed, they don't need anything else. If you want to provide an occasional treat, there are lots of options that aren't potentially hazardous.
I concur with the other greeters, tomatoes are fine, the leaves are not.
For baby chicks...like said above, they should only get their chick crumbles until at least a month old, and then if you give them something else, very small quantities first, and provide grit.
A "treat" they can have is wetting their mash. I use a couple of plastic peanut butter lids to put some crumbles in, spray water to soak them, sit them in the brooder, and watch the chicks go wild!
Scrambled eggs are one of the safest first treats that most chicks tolerate well. We start them out with a very small amount the first time, after they're about a month old. We wait until they're about 6 weeks old to start anything stronger like fruit and veggies. Always make sure they have grit though if giving them anything other than their feed.
Welcome to BYC! We have tomatoes in a garden that is fenced off from our chickens, though there were a few times early on that some of our girls found a way to sneak in the garden… hahaha. Our chickens have never gone after the tomato leaves or anything else they should eat… except we had one eat a piece of plastic on our watch! Crazy girl.
Welcome. Your chicks and chickens cannot have tomato leaves or green tomato's (unripe). They contain solanine and are toxic. I do occasionally feed my chickens ripe tomato's