If the window isn't frosted, then the source itself is still the bounce frame -- the window is basically acting like a flag. So whether the 6x6 or 12x12 outside is softer depends on how close the subject is from the window... from their position, maybe standing near the window, can they "see" the larger 12x12 frame compared to if there were a 6x6 frame out there? If so, then their face will show the difference between being lit by a 6x6 source versus a 12x12 source.
However, if they were deeper into the room so that from where they were, they could only see a portion of either the 6x6 or 12x12 frame filling the window, then the softness of the light would be the same because the size of the source was the same from their position, it would be limited to the size of the window. However, for the rest of the room, the larger 12x12 source would spill light into the room side to side more than the smaller source would.
The distance from the window to this bounce frame is also a factor in all of these interactions.