This is a Standalone expansion pack released after Dishonored 2. It is somewhere between 7 and 12 hours long depending on how many of the Extras you finish.
I don't think this gives access to the new content. They removed Denuvo but now you have to go onto the Bethesda Launcher to get that new stuff. Unless PLAZA found a way around it. Bethesda is really making some really greedy bad choices lately. People who got the game on Steam now have to install and run the Bethesda Launcher... :/
https://igg-games.com/how-to-install-a-pc-game-and-update.html
new content for fans