When Aubrey Plaza was cast in the second season of “The White Lotus,” on HBO, she asked the show’s creator, Mike White, what kind of role he was writing for her. White told Plaza that her character, Harper Spiller, would be “normal.” For most actors, that answer would be unremarkable, even underwhelming. But, for Plaza, it was likely a welcome change of pace. The actor and comedian, who is thirty-eight, became famous in the twenty-tens for playing a deadpan and disaffected intern, April Ludgate, on the NBC sitcom “Parks and Recreation.”