The last installment in Philip Glass’ “Portrait Trilogy,” Akhnaten follows the short seventeen-year reign of Amenhotep IV, who renamed himself Akhnaten meaning “of Aten.” The sun god, Aten, was the one god that Akhnaten believed in, making him one of the first ancient leaders to venture into monotheism. Star countertenor Anthony Roth Costanzo is the title pharaoh, with the striking mezzo-soprano J’Nai Bridges in her Met debut as his wife, Nefertiti. To match the opera’s hypnotic, ritualistic music, director Phelim McDermott has created an arresting vision that includes a virtuosic company of acrobats and jugglers.