This?
Google Search:
https://www.google.com/search?sca_esv=600582000&q=so-so+happy&tbm=isch&source=lnms&sa=X&ved=2ahUKEwjNq5LHofKDAxWPLTQIHe6oDb4Q0pQJegQICxAB&biw=1440&bih=815&dpr=2#imgrc=uphxyqGf_aqWZM
And also what aesthetic is FEMTANYL'S music?
About the image, the aesthetic of the Google image is super flat pop, but I have no idea about the aesthetic of femtanyl's music
So-So Happy was super popular among Scene for clothes at some point, but idk if that's the answer you are looking for.
What do you think?