No, floors stay parallel to the floor (flat floor). There are walls you can build which are clean like the one floor set (or the floor/roof combo set). Those walls though are almost all the way to the right of the selection slider (whereas the clean floor I think is like the first one in the floor slider).
Sometimes you need to make something custom in an area already constructed to make it "fancy".
http://imgur.com/yrS8vq8
Of course, if you really want to get super super fancy, I suggest you check out this youtube content creator (named https://www.youtube.com/channel/UCYp9-KGZn4UZzfjSomJ4hAg) and specifically his playlist about settlements. He has done some of the most amazing work, and he does it all on the PS4 (so no mods or console commands).
Im pretty sure you can recreate the pre made houses with the normal building pieces and it looks better because you can chose wall types and actually completely finish the walls.
I had used the largest 2x floor one as a model and made a bigger one based on how it looks because I almost liked it.
Those pre fab houses can be weird.