We all know the basic tips on wearing colors that fit your undertone, not your actual skin color, but have you ever heard of color seasons? I feel these are more accurate and when I wear those that fit me the best, I feel expensive even when I'm a pleb. I'm just so happy that I share the same color season with Jennie, as I can easily copy some of her 'fits if those match my personal taste.
By the way, what's your preferred colors on yourself and the BP girls? I really love darker hair on both Jennie (Deep Autumn) and Lisa (True Autumn) while I adore the blonde on Rosé (soft Autumn). Only Jisoo is different as she has a cooler undertone (True Winter), which is why she can rock that purple gown and the blue Elsa gown.
And for the people asking for Rosé to have darker hair color, I don't think she'd easily change her mind about the blonde. She looks ethereal in it, and going too dark while provide too much contrast between it and her undertone. The blonde brings out her features and it isn't a coincidence she got noticed more because of it.