H&M knows a good party: Just ask Iris Law, who was among the dozens of celebrities to attend the Charli XCX rave the brand hosted during London Fashion Week. Model and It girl Amelia Gray was also there — and she also turned up for H&M’s blowout block party in New York on Oct. 9. Celebrating the best of the city’s music and fashion — and H&M’s just-dropped Fall/Winter collection — guests including Lucky Blue & Nara Aziza Smith, Riley Keough, Emily Ratajkowski, and Mona Tougaard all showed up on the Soho street behind the retailer’s Broadway outpost for a late-afternoon music festival. Kitty Ca$h, Kaytranada, and Channel Tres all took turns spinning for both attendees and the hordes of onlookers who were lured by the throbbing bass (and the possibility of catching a...