My "normal" size in Kut is 2. (It corresponds to my normal size in other jeans and pants, like GAP, BR, J. Crew, etc. In premium jeans I am anywhere from 25 to 27 depending on the brand, cut, and/ or fit that I am looking for -- skinny, slouchy, etc.)
I ordered a size up in those pants for a slouchier fit. (Size 4) I haven't yet worn (except to try on and cross the border, LOL). I don't think they will stretch a lot because they are not very snug. I need to wear a belt to keep them on.
My Kut Diana skinnies are size 2 and they DO stretch out enough to make them fit like slim BF jeans on me after an hour or two of wear. I actually like the fit of them. Aida's do the same -- but Angie has other clients whose Dianas never stretched a bit. SO...YMMV.
ETA: Increasingly I find that I am sizing up in my jeans, as a matter of course. I seem to like the slouchier fit. So I also bought a pair of GAP real straights in white to wear as cut offs this summer --- and sized up to a 4 in those, too.
Also sized up in my CoH Racers (to a 27...but they do fit very slim anyway); sized up in my Rag and Bone Dre jeans, too. Hmmm.