I don't think there is anything like that available. If you want the room to be 4 x 4 or 5 x 5, then just pulling out one regular wall (one that follows the grid) to the correct size and then the perpandicular wall to the same size works in keeping the shape. However, if you want something bigger, than honestly, it's a lot easier to just use the single wall tool and draw it out. Once you draw in the final piece of wall, it will recognise it as a room and you can pick it up and move it to where ever you want.
You can resize a small octagonal room and keep it's shape, but you need to pull out the walls in a particular order and then push others back in. It's not worth the hassel when you can just draw it out to the size.
