Kat has gotten quite adept at recognizing the potential in the clothes her mother no longer wants. That bleached denim jacket was hers. So was the Gap sweater. The jumpsuit she's wearing underneath those, however, she scored at Goodwill. Same skill applied in a different venue. The boots are Doc Martens, though I didn't recognize them as such without the signature yellow stitching. Kat never much cared for that stitching.
What works so well about this outfit for me is that none of it should work together at all. It is pieced together, almost haphazard. It is not on trend. It is not easily identified as some recognizable type. Instead, it creates its own visual vocabulary.