It’s not really “passion.” As one of the former S deans noted, no one seriously expects a hs kid to have real passions. This is more about “vision” and follow through, how one identifies the right sorts of challenges, goes after them and develops resilience and perspective.
OP, you get a feel for what Stanford wants by reading what Stanford says it likes and needs. Otherwise, it’s a shot in the dark. Get researching, be proactive.