Known as a hotbed of innovation, Opera Philadelphia’s Festival 019 presents four operas in two weeks. The world premieres are Denis & Katya (Romeo and Juliet in the age of social media) and Let Me Die (an “aria-logue” that splices operatic death scenes into witty storytelling). Prokofiev’s The Love for Three Oranges and Handel’s Semele round out the festival. —L.J.