Apart from the acting, I can't disagree more. Nothing about that movie felt real to me at all. Even chalking it up to Hollywood dramatic license, very little of the dialogue felt authentic to me, apart from Woody. McDormand was good as usual, but not her best role. Definitely doesn't beat Olive Kitteridge, which IMDB now reminds me was a miniseries and not a standalone movie. I thought her lines really felt forced though. Poorly written dialogue. I enjoyed Rockwell, but he was an oaf and again a caricature. Nothing real about him at all.
Also watched Darkest Hour and Lady Bird. Darkest Hour was an Oldman show, as most of his movies are. He was great and deserving of the Oscar, but honestly I'd have a hard time choosing between him and Lithgow when it comes to Churchill portrayals of the last few years.
Really enjoyed Lady Bird. It felt much more authentic than Three Billboards for sure. Came off like a John Hughes movie, and that's not a bad thing. The acting was excellent all around.