Ever watched literally any Fantasy-themed Ghibli movie, The Ancient Magus Bride, Suka-suka, Made in Abyss, or Kuutei dragons? They all have this recurring theme of a unique, fantasy-heavy world. Not the typical elves and schmelves, orcs and goblins, etc. They have their own interpretation of the genre, and it feels like they have a world of their own as compared to stories with the main worldbuilding as "our world but with fantasy". How they depict and illustrate their worlds and characters is so colorfully unique and different, fresh. How they go about their worlds' story is so immersive, as if they truly have cultures that span millenias. I personally believe such stories to be my ideal of the fantasy genre. Know more beauties like these? And also, I'd like to avoid heavy dark fantasies for now.
I think stuff like kino no tabi and Tensei Shite High Elf ni Narimashitaga, Slow Life wa 120-nen de Akimashita have a very nice fantasy setting. Kino is more of a realistic fantasy, while the high elf one is a stereotypical fantasy both have adventuring and slice of life that I really like
100% on Kino no Tabi, I was planning on including it for my examples but felt it was too dark for the selection. High Elf... yeah I'm not too keen on that. It checks off too many clichés, but I'll give it a try.
Mushishi comes to mind based on ur parameters. Although it is episodic, the world feels authentic, and the fantasy elements feel unique and organic. Ultimately quality writing, animation, really Art period, is rare and can't be mass produced. The demand far exceeds the supply. If Studio Ghibli is your standard, very few creatives can pass that bar.
Twelve Kingdoms If you're into world building in fantasy novels, this is the place to start. As far as I've seen, it does a better job of this than anything other Japanese work. It also has some of the strongest characterization I've ever seen in light novels and it even has an excellent anime adaptation. Arcane If you have access to Netflix, you should watch this show. It is one of the best animated anythings ever, and it has one of the most immersive fantasy worlds ever detected. Yeah, it's based on a video game but you don't have to know anything about it to enjoy the show.