They could, but a box is not that attractive when they are looking for a new home. It is believed that the swarm is looking for a certain amount of space and the catch boxes I use are pretty close to that space requirement. They are looking for someplace to make their home that is big enough that they can grow and build their comb. I'm just going off the information that my mentor that has been keeping bees his whole life told me and so far it has worked out pretty well. I have another friend that tried using deep hive boxes as catch boxes and didn't catch any swarms last year. Best practice is to get them moved from the catch box to a hive before they start going crazy building comb all over the place.
So, could they see a hive that is empty and move into it, sure. It happens frequently. Will they take to a bigger box with more room more readily, I think so. Kind of like buying a house vs. apartment.