LotR is amazing for so many reasons. Most stories are kind of Potemkin villages. You see just enough of the surrounding world to carry the story forward. The characters pass a church, and the old stone might be described to give atmosphere, but you know, it’s just a church, we all know what churches look like.
With Tolkien, there’s not just a church, but a whole priesthood and religion inside, along with a sacred language to go with it, and a history that ties in with many other similar “throwaway” details.
Aaron Sorkin is the exact opposite. He eschews the advice to draw up a detailed backstory for each character, saying that if you make a note that the character is from (say) Indiana in your bible, then you are forever limited. One day you are going to pull out that detail, just because it is there, and there will be no need for it in the story, and worse, if your story could be improved by having the character’s hometown be the same as another’s, then you have denied yourself that improvement.
I think I prefer Sorkin’s approach. Tolkien loved that “sub-creation” aspect — and it shows — but it’s a lot of work to do all that, and you’ve really got to enjoy it.
And you really should be making use of all that work in a continuing series of books. Tolkien did, kind of, but the books that were published alongside the Hobbit/LotR set never had the same appeal, and most were published posthumously.