Unfortunately Fallout: New Vegas is the only game I can think of that can top Skyrim. I know you wanted a newer game, but that's the best I can do.

Have you considered Cities Skylines II? It also scratches the same itch for me, and by that I mean that it has robust mod support and can be played forever without me ever getting bored of it.

Echoing what others said about the Witcher 3. I have over 1500 hours into both games. Skyrim is great if you like open world games with minimal storyline and just want to explore. Witcher 3 is very story heavy, but you can also just spend hours and hours ignoring the story and exploring the world. There's quests and random little treasures and easter eggs hidden everywhere. In the Witcher you can climb up a mountain in the middle of nowhere and come across a treasure chest or a skeleton with a book of poetry, or wander through the wilderness far away from any map markers and stumble into a side quest or an interesting place to explore. It's also just heartbreakingly beautiful.

The story does follow the events of the books and the first two games and is more enjoyable if you have experienced them, but the first time I played I hadn't yet read the books or played the other games and it still stole my heart and became my favorite game. You might not fully understand the politics or the characters or the choices you're asked to make for certain supporting side quests, but there's a good journal where you can read everyone's backstories and all the information you need for choices regarding the main quest is in the game.

OpenMW

You could try the remake of gothic 1 thst released last week. Thats not such a vast open world, but still a very nice RPG.

Keep an eye out for updates on Skywind, soon you'll be able to play Morrowind in Skyrim. They're excitingly close to finishing, after a long road.

Enderal. Which is... a skyrim mod. Although calling it a mod does it a disservice, it's a whole new game.

I loved Skyrim, considering going back to that well soon. I'm on my 3rd playthrough of cyberpunk 2077, I've embarrassingly got 470 hours on that game. I feel like those 2 games are somewhat similar, 1st person open world, player choices have some effect on the game but not much, character customization is a lot of fun, side quests galore, lots of lore, tons of mods, etc.. cyberpunk had serious troubles when it first came out but at this point it's a solid game. I recommend giving it a try

Deoends if you want to stay in the fantasy setting. Cyberpunk will give you that same type of feeling but just in the sci-fi genre.

Kcd2.

If you want the same world building and hadn't given it a try, Elder Scrolls Online is still great, can be acquired for cheap (even the base game has a lot of content), and be played almost fully solo!

If you didn't mind the "floatiness" of Skyrim Combat, ESO is great, has a lot of world building and exploration, can be quite immersive at times, and basically has the look of a modded Oblivion.

I spent a good 400h on it, mostly on lore discovery, main and side quests, and farming not for equipment but to get furniture for my house! (and if I recall I still didn't reach the max level, not a pro-player).

I never played it as an MMORPG, but more as a coop RPG while still playing solo most of the time. So I can't judge on the quality of the MMO aspects (though the cyrodil constant battle system is quite fun and intense).

Crimson Desert

Thank you all for the recommendations. May the Dragonborn's luck be with you.

I've tried Kingdom Come: Deliverance, but that game has no magic and no grand adventure. I don't really like it.

Tainted Grail Fall of Avalon

I can't think of anything that fully scratches the same itch. There are a lot of games that do certain things better than Skyrim, and everyone here has already recommended them. But Skyrim really nailed that immersive sim vibe. It didn't just feel like a game I wanted to play, it is one I want to inhabit and keep coming back to.

Oddly, the closest thing I could think of that scratches a similar, but not same, itch would be farming sims like Stardew Valley or something.

I still miss my first playthrough of oblivion. We should be able to combine the games if they can build a data center the size of Manhattan

Though there are a lot of games with the same themes and openness, I have never found anything that really fills the feeling quite the same as a Bethesda game. Save one: Deus Ex. The original one.

for breathtaking landscapes I would say elden ring. although style of play is waaayyyyy different.

I miss games like skyrim...

The new Gothic remake.

Time to take off those training wheels and experience a real RPG.

If you need the bells and whistles of modern RPGs though then try Tainted Grail: Fall of Avalon.