“Dickinson” is many things: a period drama, an irreverent millennial comedy, an eccentric family sitcom, a wildly imaginative feminist series and one of Apple TV+'s riskier productions. In its second season, which concludes Friday, the 21st-century love letter to a 19th-century poet has proven itself a very modern feat in creative storytelling. And storytelling it is. There isn’t a lot known about the inner life of the revered American poet, a recluse who never married and for whom fame arrived decades after her death. The meticulously researched half-hour series, from creator and showrunner Alena Smith, fills in those blanks with real and imagined details about the young writer’s life at home in Amherst, Mass., with her dysfunctional family, diverse circle of friends and taboo love interests. The young folks may wear ribbons in their hair and top hats on their heads, but they speak in present-day slang, greeting one another with a hearty “What up!”