While it doesn't have a traditional "scary mansion", the film features a remote and isolated lighthouse on a rocky island, which serves as the setting for the unsettling and psychological horror story.
The film's visual style is dark, moody, and dreamlike, with a sense of creeping dread and isolation.
If you're looking for a movie with a more traditional mansion, there are many options, but "The Lighthouse" is definitely a unique and unsettling experience that many associate with the description you gave.