I say yes. But with what nightly low temps? Mine were outside at 5 weeks, and I ran a small electric space heater at night for a short while. I'm not sure it was necessary, but it made me feel better that they weren't booted from a nice cozy heatlamp brooder to a cold coop.
(The heater was not accessible to the chicks, our coop was built within a storage shed, and there's a division for storage and for chickens. )
Are you asking if they are old enough to be out of a brooder or if they are old enough to free range? Out of the brooder - Yes they are. However, if you are still using a heat lamp in their brooder they need to be weaned off of it first. It can be a shock to their system to go from being in a warm, toasty brooder to the chilly nights we are still experiencing.
Out to free range unsupervised? No.