it could be photography, drawing, painting, etc.

I know JB from Got7 is really into photography. He had his own exhibit a while back. 

I'm not sure about anyone else tbh. 

Taehyung aka V from BTS is into photography 

here you can see some of his photos

Into ARTS? Yes You looking for BIGBANG TOP and G-DRAGON . They both well know among popular artists and owned rare pieces of valuable art too.

Here some pics of them with popular artists.

It also said Seunghyun (TOP) comes from a family of artists but he is also related to Kim Whanki. His maternal grandfather is Kim Whanki's nephew.

TOP also curated Sotheby  Hong Kong  auction  in 2016 with a highest rate.

You can check some of the pieces owned by GD

They both also collect Furniture pieces too