You'll find that a lot of people do a whole lot of different things. Some of the basics for a laying flock. If you raise them for meat, it is different. This is based on feed usually available at the feed store.
Age hatch until 6 weeks - feed chick Starter, somewhere around 22% protein.
Age 6 weeks until 20 weeks or start of lay - feed 16% protein content Grower.
Age 20 weeks or when they start laying- feed 16% Layer.
The higher protein in the Starter helps them feather out and gives them a good boost to get off to a good start. Once they are fully feathered out and have got a good start, the 16% protein Grower gives them what they need to develop at a pace that matches growth with maturity. Some people use a 15% Finisher from 13 weeks until you switch to Layer, but for our flocks that is really not necessary.
This schedule gives them a balanced diet. It has all that they need. Many of us give them other things, which we call treats. Some treats do not upset this balanced diet concept, but the normal rule of thumb is to give them no more treats than they can clean up in 10 to 20 minutes. And try to give them different treats, not always the same thing. Think balanced diet.
This assumes you are giving them everything they eat. If they free range, they control that more than you do. I free range mine and still follow these general guidelines. But I don't always follow them exactly. My feed store does not always have these things. Instead of a Starter, I can only get a 20% combined Starter/Grower. And instead of the standard 16% Grower, I can only get a 15% Grower/Finisher. Mine have access to the compost heap where I throw kitchen scraps. They get a lot of waste out of my garden.
You will find that many people on this forum give their chickens all kinds of extras, some of it pretty weird and strange, at least to me. Usually their chickens do great. It just shows how adaptable chickens are. As long as you provide for their basic needs they can handle a lot of different circumstances.
I gave the basics but I can't follow them with what I have available. I have to be adaptable too.
