Yes, unfortunately, Atticus does emerge as a racist in Go Set A Watchman, and much of the novel involves the adult Scout, now called Jean Louise, having to come to grips with this aspect of her father, which reveals a side of him which she has never seen before.
Jean Louise is 26 and returning to Maycomb from New York to visit the 72-year-old Atticus. Until this visit, she had not realized how wholly he had imbibed the racist views of another era.
As the novel unfolds, Jean Louise finds a pamphlet in the house called “The Black Plague.” It is so viciously racist that Jean Louise is astounded and disgusted, likening it to Nazi German propaganda. She throws it out.
Hearing that her father is on the board of directors of a Maycomb County white citizens’ council and that Hank is a die-hard member too, Jean Louise goes to the court-house so she can witness a council meeting. The racism of the meeting sickens her completely. Jean is torn between her love for her father and her hatred of the group he is part of it.
Later, in conversation with her father, Jean Louise learns that he does think blacks are inferior to whites. He also denies that they lack opportunities to get ahead. He believes, too, that blacks are not ready for voting. Atticus is, as well, completely unable to accept the idea of racial integration.
Jean Louise lets her father have it. But when she later tries to apologize, he tells her he is proud of her for standing up for her beliefs. The two come to an awkward reconciliation, agreeing to disagree.