So first off, ubisoft wastes a lot of space with languages. Feel free to delete any you dont need.

First rick click the game in your steam library. Hover over "manage" and click browse local files. Should put you in the Assassin's Creed Valhalla folder of your common folder.

12 GB: Open the sound data folder, inside it is a pc folder. Delete every file that does not have the language you are using or "sfx" in it.

Optional quality of life choice. This doesnt save much space, only around 14 mb, but if you go to the videos tab and delete every language folder (make sure not to delete skills), it removes the launch screen videos. Make sure to delete the ubisoft logo, amd logo, and anvil logo videos as well.

So, the game installs everything, even content you don't own which makes little sense for a single player game. So if you don't have specific dlc here is what you can remove.

Within the AC Valhalla folder there are the major dlc folders. These sizes assume you already removed the languages Just delete the folder of any dlc you do not have.

11 gb: Wrath of the Druids-DLC 20

14 gb: The Forgotten Saga-DLC 35 (This is free however)

14 gb: Dawn of Ragnarök-DLC 148

9 gb: Siege of France-DLC 207

3.4 GB For any dlc you do keep, make sure to also remove the language files within there is 3.4gb in total. Just delete every different language file except sfx and your primary one of course.

So there is some stuff I am unsure about. Feel free to do some testing yourself ontop of what I did and I'll add you as contributor. I'm down 30gb to 128 rn, which is good enough for me (I removed rag and the languages). But If I could get down another 10 that would be great. I doubt below 100 is possible assuming I keep the dlc.

24 gb: DLC 211. Not actually sure what this is. Deleting it screws up the in game store, and says I am missing a blank dlc on my save. I try to load, i'm able to move in the animus area. I have no clothes but I have my weapons, and then it crashes after 3 seconds. Tried deleting some of the individual larger files within, no dice. Im assuming this is more misc stuff added over updates.

4 gb (x2): Not sure what 232 and 248 are, Best guess is the Odyssey crossover stuff is maybe one of them, but it doesn't explain what the other could be.

Rest of the dlc folders are less than a gb in size.

If for some reason you want any of the content back, if you verify the integrity of the game within properties, it will add back everything included in the original install. When testing I just removed stuff from the folder but didn't delete it just in case I needed to add it back.