“Brat”, the latest major release from Charli XCX (aka Charlotte Aitchinson), may be the pop artist’s magnum opus, elevating her to powerhouse status from mainstream celebrity. The album combines the stylings of the 2000s European rave scene with group chat lingo now common among Gen Z users. It succeeds by employing a confrontational sound, as well as by providing intriguing insights into Ms. Aitchinson’s conflicted relationships with other musicians and celebrities, from Lorde (who appeared in the remix of “girl, so confusing”’” after it was confirmed that she was the song’s subject) to Dasha Nekrasova, the actress famous for appearing in the third season of “Succession” and the co-host of the notorious “Red Scare” podcast.