No business plan survives first contact with a customer
The basic idea would be to take something like that lean canvas (https://leanstack.com/leancanvas). Then have a founding team answer each section with 3 bullet points. Then they go 3 points deeper further explaining each point, and then 3 points under each of those points. You end up with a much deeper clarity of thinking than most model oriented schemas.It’s an exercise. If you can’t go 3x3x3 deep, do more research and work on articulating what you’re trying to build.
The advantage is that it doesn’t require you to be creative. It’s work, but it’s brute force work. You come out more creative on the other side.