I train my littles to come for treats, starting in the brooder & coop. I have bright orange tape that I put around the treat container (meal worms), so they can see it from a distance.
View attachment 2466301
I start treating them around 3 weeks old. I always take a minute to hold the treat container up where they can see it, and shake it a little. Then, give them each a few. It usually starts by dropping them in, so the chicks can explore & taste on their own. Then, holding one worm at a time for them to peck at. After a few days, they'll come running out from under heat plate, from the other side of the brooder as soon as they hear the shake and/or see the bright orange container. I let them grab treats out of my hands and directly out of the container. Same process works inside the coop, to get them to run over to you for treats.
Once they are ranging outside the coop, you can treat them outside a few times where they can see you. Eventually, you will be able to shake the container from inside the coop to get them to come inside for treats at any time (especially if you add your choice of chicken call, at the same time you're shaking the treat container). Depending on how many you have, it could still take a little wrangling to get them all in at the same time. You might need to close most of them in, and catch any stragglers (using treats) on the outside & carry them inside.
In my experience, chicks stay very close to the coop, even without a fence, for several weeks before they start ranging further. I usually let them start ranging on their own by 6-8 weeks (after they've gotten to know the rest of the flock through a fence), and they stay close to the coop for at least 3-4 weeks, even with no fencing. It helps with the integration that the chicks stay close while the adults range further away, so the chicks get the place to themselves for most of the day.