The story is basically the same and pretty much everything but the specific plot of Arcane came from it. League's story is one part everyone agrees is good to the point that when they ended up making the universe's equivalent to rise of the Lich King discount infinity war the entire community revolted. Arcane came out directly after that mess. Keep in mind that the main game itself is literally the standard of MOBAs so none of this is really "in game" aside from events. There's a bunch of side games/comics/ ect that is better able to show of the universe.
The story is basically the same and pretty much everything but the specific plot of Arcane came from it. League's story is one part everyone agrees is good to the point that when they ended up making the universe's equivalent to rise of the Lich King discount infinity war the entire community revolted. Arcane came out directly after that mess. Keep in mind that the main game itself is literally the standard of MOBAs so none of this is really "in game" aside from events. There's a bunch of side games/comics/ ect that is better able to show of the universe.