Well, this is not the normal advice, but personally I don't use medicated feed, I use raw garlic instead to prevent coccidiosis. Unlike when using medicated feed, there haven't been any losses to cocci when using garlic as prevention.
Their very first feed has a few cloves of finely minced raw garlic, the fresher the better. From there I can give it to them once a week or so and it's sufficient, never seen a case of coccidiosis throughout all the years of feeding chooks garlic to prevent it. A zero percent mortality rate to disease in chicks year after year after year must be worth something I reckon.
I would raise them outdoors myself, if possible, again that's not the normal advice, but I believe they grow better in real sunlight on real dirt and it gives them healthier immune systems. They certainly look better raised that way, in my experience. Synthetic vitamin D in the diet doesn't quite make up for no real sunshine. It does depend on what your circumstances are like, if it's frozen outside that's not necessarily going to work for you.
Unfortunately animal proteins are being phased out of chicken feed in a lot of places and I don't believe they do as well on purely vegan diets, the results speak for themselves. So farming insects for them may be worth looking into, or providing other sources of animal proteins, unless you're happy to raise them vegan which I think is biologically inappropriate. But that is just my opinion and your chooks, your call.
Sprouted, soaked or fermented seeds and grains are particularly beneficial to them, even if all you do is soak them overnight, I highly recommend that. They not only eat much less than if the grains were dry, but absorb so much more, it's definitely something to read up on. It makes the feed more nutritious and bioavailable so they eat less but get more out of it.
I start mine on the same diet they will get as adults, just with more protein, but what breed you get and what you intend them for, and your budget, will all have an influence on what you can do, as well as availability of feed types. Millet seeds are excellent for them, high protein.
Best wishes.