I bet they can for sure :D it really doesn't metter that much if the suit is a bit bigger for the astronaut just to be sure. It just another layer in case of decompression. The astronaut won't do anything in the capsule when they are in the suits anyway. Just sitting in his seat. You can even use pilot with properly fitted suit and training from the other Dragon that's on ISS as emergency pilot for the ride. Most likely also just sitting there. It's all automatic.