The answer to almost any question regarding 5, 6, 7, 8, 9 week old chicks is that they are a whole lot tougher than folks give them credit. A broody mom would have kicked them out out the nest a long time ago, so to speak. After 4 weeks, most chicks only need a little help at night. At 6 weeks, unless you intend to experience overnight temps in the 20's, they don't need any assistance at all. Just a dry sheltered place. That's it.
If I were leaving for a couple of days, I'd lock the birds in a safe place, like our barn or in a large coop, with twice the waterers than normal. If daytime temps were not over 86F and they had good ventilation, I'd rather they be locked up and I not have to worry about them. If they haven't figured out how to get up and down a ramp yet, they'll be left outside and perhaps more susceptible to predation.