Idols are almost always seen wearing clothes provided by their stylist or coordinator so fans rarely get to see their favorite celebrities personal fashion. Here is the list of 10 Kpop idols who get more hate in the Korean Pop industry whether they deserve or not and the reasons whether sensible or not. But if you are talking about their own clothes then idk they probably have a closet.
I think that some of the clothes that they wear especially during promotions are borrowed from the designers.
I think its highly situational. Theres also probably a lot of situations where brands and management just trade clothing for free if its mutually beneficial to both. In a new video. Idols are almost always seen wearing clothes provided by their stylist or coordinator so fans rarely get to see their favorite celebrities personal fashion.