Green’s Dictionary of Slang

(US black) a suit of clothes, esp. a well-cut garment.

1972		D. Claerbaut Black Jargon in White America 64: fit n. 1. dress; clothes; apparel. See also vines, weave. 2. a suit; complete outfit.
2024		Axis Parents’ Guide to Teen Sl. 🌐 Fit = In America, ‘fit’ is short for outfit. (‘Girl I love your fit!’).