the only anarchist position on sex work that makes sense to me is to consider it work, and to treat it like work.
and OF COURSE to reject the system that a) forces people to work if they don't want to, b) stigmatizes choices that people make, c) prioritizes and devalues sex and bodies the way christianity (among other value systems) does.
to say that sex makes it different is perhaps often true, but is certainly not necessarily true, and relies on the kinds of generalizations that get people riled up and active, but are frequently not conducive to clear thinking. (when answering this question, to take a position means to get something wrong, and the choice is the kind of wrong one is willing to be.)
human trafficking/sex slavery is a different issue - as kidnapping and slavery are already considered horrible - and adding sex to it seems like more of an obfuscation than a helpful clarification.