The Ballad of Buster Scruggs

According to the latest news it's a movie, not a series

https://variety.com/2018/film/in-contention/coen-brothers-ballad-buster-scruggs-film-venice-oscar-1202883508/

Instead of a series, The Ballad Of Buster Scruggs will now take the form of a feature film. However, it will still be structured like an anthology and will still stream on Netflix, as well as receiving a cinema release later this year.