Since Silent Hill is known for its deep and often convoluted stories, Silent Hill 6's game story could potentially revolve around a person's past traumas manifesting in the form of the terrifying Silent Hill environment. The town has a way of warping reality based on the psychological state of those who enter it. So, perhaps the protagonist has a connection to a long - forgotten event in Silent Hill's past, and as they explore the town, they gradually piece together what happened and how it relates to their own situation. They may encounter various characters, some of whom are helpful and some of whom are not, all while being haunted by the grotesque and otherworldly manifestations that the town throws at them.
I'm not sure exactly as Silent Hill 6 hasn't been released yet. But it might continue the trend of psychological horror with a protagonist facing their inner demons in the nightmarish town of Silent Hill.