Last year Mike Thornton wrote a couple of articles for Pro Tools Expert about loudness and dynamics in Cinema, including input from Eelco Grimm from the Loudness Petition Group and the results of a survey. It provides some interesting, if somewhat depressing at times, reading. You can read the full article at:
https://www.pro-tools-expert.com/home-page/2017/6/21/loudness-and-dynamics-in-cinema-sound
https://www.pro-tools-expert.com/home-page/2017/4/29/cinema-survey-results