How LOTR ends:
Frodo claims the Ring o Mount Doom at the Crack of Doom.
Gollum knocks out Sam and attacks Frodo.
Gollum bites off Frodo’s ring finger and, gloating, trips and falls into the Crack of Doom.
Frodo and Sam leave the Crack of Doom, succumb to fumes, are carried away by the Eagles.
Frodo and the remainder of the Fellowship rest for some months in Minas Tirith, then take a scenic tour back to the Shire.
Mary, Pippin, and the Hobbit’s of the Shire rise up and rout Sharkey’s gang that have occupied the Shire.
Frodo confronts Saruman (Sharkey) and Wormtongue. Wormtongue kills Saruman and and is in turn killed by the Hobbits.
Frodo is Mayor for a couple years. Sam marries Rosie Cotton and starts a family.
Frodos wounds haunt and plague him. He decides to leave the Shire for the West. Sam goes with him as far as the Grey Havens.
There they meet Gandalf, Elrond, Bilbo, and Gandalf. Merry and Pippin also turn up (having been tipped by Gandalf).
There is a final farewell to Frodo, Bilbo, Gandalf, Elrond, and Galadriel. They take ship and take the Straight Road into the West and to Valinor.
Sam, Merry, and Pippin return to the Shire. Sam becomes Mayor for many years and raises a large family.
All are great friends to the end of the days. Aragorn lives a very long life and finally decides to “lay it down” and dies. Arwen returns to Lorien, lives there a year, and finally lays down her life there.
Legolas and Gimli, many years after that, go into the West together. The last of the Fellowship.
I should have added:
The book we know as The Lord of the Rings was (in story) begun by Bilbo, nearly completed by Frodo, and finished by Sam.
Long years later, Sam turns stewardship of the book to one of his daughters and leaves the Shire, presumably to go into the West and to the Undying Lands to be with Frodo.