Can't tell you what Vienna will be like (and might be late, haven't been near my PC, sorry) but in Innsbruck, there were a few ways of doing things
First up, "Night Clubs" straight up, these aren't American night clubs. You'll essentially get a pick of women, you'll go to your choices' room, and discuss pay. I chose this route and it was about 100 euros for FS. For all intense and purposes on google maps, Night club and brothel are interchangeable terms in this area.
Second are strip clubs, to my understanding, this is same as here, you'll get a lap dance and essentially get offered more, no idea about prices here
Third are, the tried and true rub and tugs. At least in Innsbruck I don't think there was a single one, so I can't verify but I believe they're pretty much the same as America too.
Brothels are legal here, but street walkers aren't, but very much exist. Be careful, obviously we toe the line in our country but I don't wanna know the scare involved in being deported for this lmao.