Short form... without knowing your breed well, or not having a color-sexed breed and since you can't know the lines you have (fast or slow feathering if it's there) and You DON'T know with hatchery birds ever then you flat don't know.
You get to wait. Depending on the breed you will get clues at about four to six weeks, unless you picked a particularly difficult to sex breed like silkies.
Before that, with hatchery birds. It's all just a guess. In experienced hands someone who's seen 2 or 3 hundred or more chicks might have a better idea. New chicken people get to wait and see. I took pics of my first 75 chicks at one week through two months every week. The first time through I was clueless. By the second group I had a better idea and by the third group in the same breed, I had a pretty good idea by the second week.
Then I got two different breeds. Nope can't tell at all. Totally different development patterns.
And turkeys different again.
Mostly keep track of your feed costs and wait and when you get to four to six weeks out you'll have a much better idea and can sell them off. Feed costs let you know what to charge.
Good luck, what breed/s?