The film's power comes in large part from Epstein's excellent and realistic screenplay.
in large part
Mostly; to a great extent. While we've all been working very hard, our team's success on this project is in large part due to Sally's efforts.
in ˈlarge part
,
in ˌno small ˈpart
(formal) to a large extent: The speech was in large part an attack on the Prime Minister.She was in no small part responsible for the success of this company and we mustn’t forget that.