Julian Fellowes' The Gilded Age makes more changes to history than his previous show, Downton Abbey. In the newer series, the lives of Marian Brook (Louisa Jacobson), her aunts Agnes (Christine Baranski) and Ada (Cynthia Nixon), and other fictional characters are interwoven with historical events of the 1880s. Different storylines depict or are inspired by New York's Opera War, the Homestead Strike, and the work of several revolutionary figures.
https://screenrant.com/the-gilded-age-season-2-true-story-changes-history/