How can you design a user flow when you don't know the functionality?

1. What makes a good user flow?
2. Which shape can be used for user to decide which flow need to be taken?

What makes a good user flow?

Great user flows start with an understanding of your user journey. Creating a great user flow requires a deep understanding of a user's typical journey with your product. You want flows that nurture them through onboarding, show them the ropes with your features, make using your product a breeze, and so much more.

Which shape can be used for user to decide which flow need to be taken?

Rectangle. The rectangle is arguably the most common shape used in user flows.