If you by only original game without DLCs, DON'T play the game in current patch, but change to version 1.5/ 1.7:
https://forum.paradoxplaza.com/foru...patch-level-of-europa-universalis-iv.1009270/
Prior to 1.8 DLCs did not really influence the game much. However, later most mechanics to play the game became locked in DLCs.
So, you need to buy DLCs in the order of their appearance (and change versions to the relevant patches + 0.1).
I.e., if you buy Art of War, change the game version to 1.8+0.1 = version 1.9