Obviously, actors Daniel Radcliffe (Harry Potter), Emma Watson (Hermione Granger), and Rupert Grint (Ron Weasley) will all be there. We can expect the key Hogwarts students and teachers, as well as He-Who-Must-Not-Be-Named. The show itself is divided into four chapters, highlighting two movies per chapter. We can expect a ton of clips, bloopers, and behind-the-scenes footage, as well as the actors chatting about their experiences being part of a franchise that changed their lives forever.
Source: https://www.distractify.com/p/is-jk-rowling-in-the-harry-potter-reunion