Welcome!
I've had lots of types of birds over the years, but only got into chickens almost 4 years ago. I always keep the nutritious layer feed, a mineral block, a mix of calcium/mineral grit/crushed egg shells from when I make hard boiled eggs (in a plastic feeder since grit will ruin galvanized) available for my birds at all times; so with chickens that would be their pelleted layer feed, and I use a hanging 2 or 3 gallon feeder, there is always layer feed in there for them, and as birds naturally forage most of the day, I think there should always be that healthy kind of feed available. They like their foraging and greens, too, but over the winter that is difficult here, so I do give them some meal worms and a cabbage to peck at, a good sized cabbage head hanging will last about 3 or 4 days, and they only peck at it now and then, so they do eat the layer feed mostly. I also grow chickweed and will grab a hand full once the cabbage is gone, so they eat that fast, gone within 1 minute. If I have some salad greens or veggies left over from dinner, I cut in small pieces and spread on a cookie sheet, and will serve, again it's all gone within a minute, I wait til they're done then take the cookie sheet to wash off and be ready for next time. They like just about every veggie that I do, squash, zucchini, green beans, peas, lima beans, tomatoes, melons, etc. Just NEVER give avocado or citrus fruits, not good for them. Once a week, I will give them some cracked corn mixed with mealworms, I use a small coffee can to measure, on Saturday or Sunday when I am hanging out with them. It's a good time to handle them when you bring treats, sit a hen on your lap, and make sure everyone is doing good. When I rescued some of mine, they had lice and bumblefoot, so now I just handle all birds weekly to not only keep them used to me holding them and be relaxed, but to take that opportunity to see how well they're progressing. I try not to give too many treats in general, a little here and there, but not every day, because I want to make sure they have proper nutrition, since laying eggs daily is a lot of work.