This year will mark the 25th anniversary of Natalie Portman’s film debut in “Léon: The Professional,” where she played a 12-year-old child assassin. In this week’s “Sunday Sitdown,” Willie Geist talks with the Israeli-born actress about the ups and downs of her long career since then, which included a four-year break to earn a degree from Harvard. She also opens up about the dark role she takes on in her latest film, “Vox Lux.”