Here is the full list of all 12 Lust from Beyond: Scarlet achievements. It takes around 1-2 hours to unlock all of the achievements on Windows.
Finish the game.
Escape the theater by killing all the members of the Scarlet Lodge.
Collect all voodoo figures.
Examine all objects containing text.
Finish the second trial.
Finish the first trial.
Meet with Rhea.
Press the piano keys 50 times.
Listen to the recording from the voice recorder in a secret room.
Escape the theater without killing anyone.
Have sex intercourse for at least 3 minutes.
Solve the puzzle in the theater with the least number of spins.