Not gonna lie, I just started playing CK2 (because I was intrigued by CK3) and it's awfully confusing.
I spent 2 and a half hours watching YouTube tutorials and i'm STILL confused.
Is the game mostly a waiting game whereas your decisions that were made take time to come fruition?
It's definitely a slow burn game, but I guess I'm really unsure when I'm making progress or when I'm just lost.
It's meant to be a very deep game that takes a long term to learn everything, but it's not at all insurmountable and becomes very manageable once you get your reps in. You may have heard by now, but the ideal starting location is Ireland, since you only have to worry about a few small rivals on your island before you can consolidate the kingdom, then start worrying about the rest of the British Isles.
Initially, you do want to resolve the major notifications along the top of the screen, then you can let the game clock start to tick and resolve events as they come in. However, you absolutely want to have a greater territorial goal you're constantly working towards, like forming a Kingdom if you're a Duke or conquering all of the Counties that should be under your Kingdom by Law. Look to your vassals and see which ones are discontent and give them Council positions, minor titles or gifts of money to have a more favorable impression than you. If you have powerful vassals whose opinion of you seems irreconcilable, you can plot an assassination and invite collaborators, offer a marriage to one of your family members to prevent them from declaring war on you, or check which of their own vassals dislike them, to provoke a lower tier civil war in their ranks.
Look at the realms outside your kingdom with whom you have non-aggression pacts and see which ones might be up for an Alliance. Offer to join their wars and you can leech off of their opponents with sieges on their undefended Counties or battles against their stranded armies to make extra gold. The more you contribute to your allies' wars, the more you're rewarded if they win.
Look at the succession laws in your country and ask whether they will be favorable to your goals when you die. Work to change the laws by placating vassals to ensure their votes to strengthen your succession.
Yes, some of this is a "waiting game," and you can toggle the game speed depending on how actively you are engaging the menus at the current moment, but you should be constantly expanding and consolidating your power, shoring up your succession, and engaging in world events through law, intrigue, diplomacy, and warfare.