Dubbed the Barefoot Soprano by an online following, 21-year-old singer Kristyn Murphy is using her nickname to lace her artistry with a carefree professionalism that she is using to break away barriers between genres, and make music, especially classical music, more accessible to audiences of all types.

“I don’t take myself too seriously. The things I do, yes, but not myself,” says the crossover singer whose approachable style blends together elements of the Classical, Broadway, Celtic, Pop...