Eventually, in Resident Evil Village, you will need to solve a piano puzzle to get a key, so here's how to do it.
How the Solve the Opera House Piano Puzzle in Resident Evil Village
In short, to solve the piano puzzle in Resident Evil Village's Opera House, all you need to do is line orange dots onto notes you will see when you find and interact with the piano.
That said, if you don't know where to find the puzzle, you can find it in the castle's opera house, which can be found on the left side of the courtyard when you leave the main part of the castle.
When you find the opera house, you will need to locate the piano downstairs, and to start the puzzle, all you need to do is interact with the piano.
Once you find the piano, you will need to line the dots up to solve it. To do this, all you need to do is select a key, and when you select the correct order of notes, you will solve the puzzle. If you have trouble solving the puzzle, the left keys on the piano are lower notes, and the right is the higher notes.
After this, a secret compartment will open, and you will find an iron key inside. You will need this key to open up a locked gate old town and possibly more doors and gates later in the game.
For more on Resident Evil Village, we recommend checking out both Resident Evil Village: How to solve the Statue Puzzle in the Hall of Ablution and Resident Evil Village All Trophies List