If she is only 6 weeks old the ears should be up as they go up at about 3 weeks.
Typically Ragdoll ears stand up and flare a bit out to the side.
Ear mites or ear infections can cause the ears to fold.
I'd plan a vet check up for your new kitten to see if it has an ear problem causing this.
This might be a genetic mutation such as the one seen that produced cats with folded ears like the Scottish Fold does. Those show up every once in a while in cats. But ear mites would be a common reason to see this.
Hope this helps you!
Cat Health, Behavior, Care Expert
30+ years cat owner, rescue, breeding, study of behavior & health care