Knights of Honor, was published by Paradox Entertainment back in the day and developed by Black Sea Studios.
Definitely give that try if you like Total War, it's a casual game with a decent strategy element.
If you're looking for something modern, Stellaris is the go-to for an introduction to Grand Strategy. I also highly recommend Cities Skylines which is published by Paradox Interactive, and developed by Colossal Order, very fun, an easy to get to grips with game.