Do you mean any example of multiculturalism done right? Or specifically in “our world” setting?
If it’s the first one, then “The Wheel of Time” by Robert Jordan/Brandon Sanderson (the latter finished the series’ last couple of books after Jordan’s death) and Brandon Sanderson’s “Stormlight Archives”.
In Jordan’s books you can see a lot of “proxy cultures”, but they’re still fairly unique and, most importantly, done right.
Sanderson’s setting is “way out there”, very unique and very different (or maybe I’m an uncultured swine and someone with a better understanding of cultural diversity on Earth would disagree).
Wow, this is brilliant! Now all I need is proper mouse gestures support and I can migrate full-time!