Oh man you have a lot to dive into then. Rosé is a global ambassador for YSL, Lisa for Celine, Jisoo for Dior and Jennie for Chanel. I don't care much for Dior and Chanel but I love Saint Laurent. Also been a Celine fan ever since Hedi Slimane became creative director.
Hedi also does a lot of the photography for Celine (and Saint Laurent previously, while he was creative director there) campaigns including this one with Lisa.