Jem Aswad Senior Music EditorThe transition from bedroom pop to one of New York’s biggest stages is not an easy one — the intimate sound and emotions of the loosely defined style are almost the polar opposite of the big gestures and loud volume it takes to fill a major venue. Yet two of the genre’s most popular (and youngest) artists, Clairo and Arlo Parks, did it with ease Thursday night before an impressively full crowd at New York’s historic, 6,000-capacity Radio City Music Hall.Parks, 21 — who is nominated for two 2022 Grammys — is already a major star in her native England and is the more animated performer of the two, although Thursday’s show represented a big step up from her last area performance (at the 650-capacity Music Hall of Williamsburg in September).