Any starter or start and grow feed will be fine for now. 18-20% protein. By the time they're 12 weeks you can cut back on the protein a bit to 15-18% range.
Don't start layer feed (4% calcium) till they're laying. Better yet, since you have roosters, provide an All Flock or grower feed when they start laying and provide crushed oyster shell in a separate container for calcium for the hens.
Baby chicks grow fast and need more protein. As they reach full size, they need less. Excess protein for older birds has to be processed by the liver and is discarded turning into ammonia in the bedding. Adult roosters need very little protein. 13-15%. Hens in production need a little more because they're pumping out a lump of protein every day.
Starter feed is crumbled finer because baby chicks have smaller mouths, esophagus and crops. Grower and all flock feeds are larger particle.