A mod is a modification of a game - and there are plenty of goods mods to use in MTW.

I would suggest XL Mod and BKB Mod to start with, both amazing works.

XL Mod - https://forums.totalwar.org/vb/showt...l-Total-War-XL

BKB Super Mod - https://forums.totalwar.org/vb/showt...-BKB-Super-Mod