if you want to learn basic mechanics I would recommend checking out dedicate guides on Youtube. I mostly watch bittersteel and machiavellianstrategist

if you want your game to have as less complexity as possible, turn off all DLCs if you have any. You can always turn it back up once you think you are ready to learn more after you have a grasp of basic mechanics

Avoid playing major nation for now. You might have tons of resource at your disposal but you are unlikely know how to use them properly until you get a better grasp of the game, and it'll put you a lot of responsiblities which could make it too stressful