Free ranging... how much room?

keep them in the neww coop for a few days or a week....till they know that is their new home.......let them out early evening while it is still light for an hour or two...
they should go right back in the coop on their own to sleep.....do this for a couple days...each day giving them more time to be outside....then they will roam around but always
come back to the coop to eat and sleep!

Exactly what I did and it works perfectly.

Do you have a barn?  Are chicken friendly farm dogs present?  How old are birds?

Once they are about 12 weeks of age, if dogs are always about they can be allowed to roost in barn without confinement.  Mine would roost on manger or hay rack or other elevated position.  Dogs can keep predators of all sorts away.  Your run should be covered until chicks get some size or dogs are always close by.

I have 2 acres but my chicks even after a year stay close to the house. They like th bushes and mulch. They do go in nearby woods but don't stay there very long. The u more u handle them the friendlier they'll be.Try giving treats on ground and gradually from ur hand. Talk to them constantly. Pick them up letting them out and tucking in at night. This is a good time to check for bugs and injuries.

We live on 70 acres. Our house is about 300' or so from the barn, they go at least another 150' past the house in the barley field. And at least 500' the other direction. They like the seeds, and bugs. But they are very weary of their surroundings. They will not go anywhere near a barking dog. They have a very strong instinct for survival.  As long as the boxers are behind a fence, they wont go near them. If they are not behind a fence, the boxers will come and get them so that would need to be addressed.

When I put mine in the coop at 21 days I put three 4x8 panels of rewire wrapped in chicken wire in a loop outside the door for about a week or so. They latch on to the coop pretty quick. They like safe places to sleep, and they will recognize the coop as one. They took a while to venture out, but once they recognized safe areas they venture, Not-so-safe areas they stay away from.

goldies method is the one I used, it worked great. the chickens know how to take care of themselves pretty well. Mine have a bout a hundred foot range from their barn and have never seen most of our 2.5 acres, even though they free range all the time.

also, you have speckled sussex? me tooo, I love them but the two that I have have been SO slow to warm up to me, it must be in their blood.