EUIV has lot in common with Stellaris in that you're running a country, and while you have a ruler that gives certain bonuses and maluses, you're tied to the country, not the ruler's dynasty. You'll probably spend a good couple of hours in menus looking at stuff starting off, but I learned to play EUIV mainly through trial and error (and occasionally getting tips from Let's Plays). Start off by playing easier countries like Castille or the Ottomans.
The only system I'd describe as being really hard to learn is trade, but unless you're playing a nation that cares a lot about trade, going with what the game gives you and using merchants to direct trade to your home node or collecting in places where you have high numbers is pretty good. The main difference between the games is that EUIV uses mana, which is a set of resources you save up to get tech, but can also spend on a lot of other things too, and that's one of the core parts of the game.
If you're looking to jump in, but aren't sure what the game is worth to you, the $1 tier is a pretty solid starting point, although the Average Tier DLCs are definitely worth it for that price if you like the game (Most of the $17 DLCs are newer ones I don't have, so I can't comment on them).