Ronnie Fieg , the auteurist owner behind New York City’s luxury streetwear brand Kith , has turned his taste into a burgeoning global retail empire, fueled by nostalgic pop-culture collaborations with The Simpsons and Curb Your Enthusiasm and the support of the likes of Travis Scott, The Weeknd, Drake and Michael B. Jordan. In recent years, his expansive designing brio has expanded to cars with BMW, boats with Cigarette Racing and a private Kith padel club in Manhattan’s West Village that includes an Erewhon tonic bar. “I’m world-building,” he tells The Hollywood Reporter during a sit-down on the patio of Kith’s sprawling new Los Angeles flagship store on Sunset Blvd. The Jewish, Queens-born Fieg — who spent 15 years working his way up from a stockboy to a general manager at a decidedly unchic mom-and-pop shoe company before finally breaking out on his own — calls to mind both Ralph Lauren (“the GOAT”) and Marty Supreme. “I was so much more than that,” he says of his career start.…