All jeans stretches whether its 100% cotton or cotton/elastane combo. The ones with elastane will keep its shape longer though. But at the end they all do.what I have experienced is the ones with thicker denim/weight don't stretch as much as the lighter ones.
I also try to size down on some and ending up with uncomfortable thigh. So I just get my regular size, wear a belt when waist gets loose. At least my thigh doesn't look like a sausage.