It goes a little further with Tolkien. His works weren't just stories, they were the stories, myths and legends of fictional peoples and he allowed for misinformation and unreliable narrators. A reason for the lighter tone of the Hobbit compared to LotR is the fact it was Bilbo's story he used to tell to the young Hobbits so the more brutal parts would be toned down. Also in LotR you may remember talk of Bilbo initially lying about how he got the Ring and Gandalf having to bully the truth out of him. This is a reference to early editions of the Hobbit which had a very different encounter between Bilbo and Gollum when the Ring was just a ring. This was retconned in later publications after Tolkien made it part of his grander and more serious Legendarium.
The Silmarillion is the bundle of translated papers Bilbo gives to Frodo along with the Red Book. When Tolkien decided he preferred the idea of a round-world cosmology and orcs being created from Men rather than Elves he made it so the original texts were Sylvan and Mannish legends written by people who didn't know the actual truth.
There's also a late version of Galadriel's story in which she meets Celeborn (then called Teleporno) in Aman and they sail to Middle-earth together in the wake of the Noldor rebellion. Despite it being written quite late it's hard to consider it "canon" as Tolkien said it was written for "philosophical rather than historical reasons."