The big 1.5 update for Stardew Valley is here on Switch. It should be going live automatically, though you can also force the patch to download via the system’s home menu.
ConcernedApe has previously said that version 1.5 includes major late-game content. It’s been described as “by far the biggest solid chunk of new content that’s been added to the game since launch.”
In case you missed it, you can find the entire changelog for Stardew Valley version 1.5 here.