Ditto on all said above.  

Texas summers get brutal, but my Orpington girls made it through their first Summer last year with some help from "Mom".
We bought sun screen tarps that cover both ends of run where there is no tin roofing, only chicken wire, & have them drape over 12-18 inches along the side walls also.  We left one side up year round, and removed the other during the winter when they were more likely to want that sunshine.
That tarp will go back up in about a month or so.
I also froze 1 gallon water bottles & placed in the plastic tub & the hollowed out tree stump set up as a dust baths.  The girls cuddled up next to them. I rotated those out during the day as they melted. Also offered them chilled watermelon halves & frozen blueberries in the afternoons.
I tried some cute IG or Pinterest frozen water treats with frozen berries in them, but the girls weren't fans.  They did look really pretty, but no point if the girls just let them melt w/no interest in them.
I also sprayed the run down once we were getting close to the hottest point of the day.  The girls appreciated the cool ground & would immediately go scratch up a dust bath in the non-grassy areas of their run & chill in the cool earth.
We have only gotten to high 80s so far this year, but now that they are older & free-range during the day, they have many more options of shady spots with a breeze that they've discovered on their own & go to at various points during the day to chill.
Once Summer gets here, I'm assuming I'll use the same methods that worked for us last year.  Only addition so far is the additional water containers I've placed throughout our property so they don't have to go all the way back to the coop for some.
Good luck with your new babies & enjoy every minute of their cute fuzzy days as they grow so fast!
I think you'll absolutely love them cause IMO Orpingtons are just the best!
Here's a pic of this year's babies: BBS Orpingtons being raised by broody buff that I raised last year.