“Map of the Soul: 7” — the K-pop juggernaut BTS’s fourth Korean-language full-length album — just debuted at the top of the Billboard chart, though that’s only one indicator of the group’s still-growing global dominance.

In the past few years, BTS has become the worldwide standard-bearer for pure pop, a collection of seven members — J-Hope, RM, Suga, Jungkook, V, Jin and Jimin — who are charismatic, limber and, most crucially, game for the level of work and ambition required to be mega-popular at home, in the United States and almost everywhere in between.

BTS is soaring so high, it might not seem on the surface like it’s navigating particularly tricky waters. But the relentlessness of the group’s success obscures the fact that it’s on the cusp of two key transitions: a decreasing reliance on hip-hop and an increasing flirtation with high-profile English-language collaborators. “7” ends up as a kind of referendum on the sort of pop megalith BTS is becoming, and what it might have to leave behind on the way.