If you want to play an older version of the game with more then just SFO follow these steps.

1: right click WH3 and click manage
2: click browse game files.
3: path should be something like (drive/steamapps/common/total war warhammer III
4: click on the steamapps path
5: in STEAMAPPS FOLDER CLICK ON WORKSHOP
6: SCROLL TO BOTTOM OF WORKSHOP FOLDER AND SELECT CONTENT
7: there should now be a bunch of numbered folders FOR ME WH3 IS CALLED (1142710)
8: BEFORE AN UPDATE IS APPLIED COPY THIS FOLDER ELSEWHERE
(IF YOUR GAME IS SET TO UPDATE ON LAUNCH THIS SHOULD STILL WORK)
9: AFTER YOU ROLLBACK THE GAME COPY THIS FOLDER BACK TO WHERE YOU FOUND IT
10: if you saved your mods before updates were applied you can now just copy this folder into your workshop/content folder when a mod updates and you need to revert it.

PSA I would advise copying your mod folder when new updates to the game are announced as you can use this to rollback for as long as the old versions are available.