I have a flock of 39 in three different age groups. I have always let mine free-range all day even when the first group was only 3 weeks old. They were outside in a run from 4 days old (they had access to the run from hatch, but they were big enough to navigate the ramp at 4 days) and at 2 weeks, I opened the run to let them free-range late in the day each day and then at 3 weeks, I started opening the run door in the morning and letting them free-range all day.
When they were little, they stayed close to the coop, which is right along the edge of the woods. They have plenty of cover under the shrubs along the trees, under the coop, under the house and deck, et al. Even as chicks who had never seen an adult chicken, they were already tuned into the fact that cover is good and being out in the open is bad. As they got older, they ventured further out, but still had cover under cars, the boat, woodpile, shrubs, et al. We have an acre of property and half of it is wooded. The chickens have full access to the whole property all day.
Predators are your biggest concern. The chickens are fine to free-range; it's the predators that you need to worry about. To date, my biggest worry during the day is aerial predators, so making sure the chickens have plenty of places to take cover is a priority. At night, everyone is locked in the coop, so I have less worry about nighttime predators though I will set a live trap if I suspect I have one hanging around after dark.
Even though they all free-range all day, I make sure they have free-choice chicken feed and I feed them a 22% meatbird feed. I like the higher percentage of protein in the meatbird feed. If they eat less of it because they get food elsewhere, at least I know the feed they do eat is high enough to offset.
Also consider growing some forage for them if you plan to free-range. You can do a search for "forage grasses" or "forage seeds" and find plenty of forage blends that you can use to seed areas of their range to provide nutritious greens for them to feed on.