Allaah has commanded the believers to cooperate amongst themselves in righteousness and piety, and He has forbidden them to cooperate in sin and transgression. He said (interpretation of the meaning):
“Help you one another in Al‑Birr and At‑Taqwa (virtue, righteousness and piety); but do not help one another in sin and transgression” [al-Maa’idah 5:2]
According to the shar’i principle set out by the scholars: “The means are subject to the same ruling as the ends.” So everything that leads to haraam is also haraam.
Selling haraam clothing such as short skirts and tight pants etc in which women go out is undoubtedly haraam because it leads to forbidden wanton display of their charms, by means of which women tempt men.
Those who buy these clothes usually go out and appear in them in front of people, so selling them is helping in sin and transgression, and spreading immorality and evil among the people.
https://islamqa.info/en/answers/42564/ruling-on-selling-haraam-clothes-to-the-kuffaar