This template will be specific to an RFP for an app; i.e. "an app that does X".
Tell the story of what needs to be built. Articulate what is needed at a very high level in one or two paragraphs at most. Outline:
Once you've articulated what is needed, now you can:
Depending on the project, you'll want to include different sections below.
Outline each type of user that is going to interact the product. Who are they? What is their goal when using the product.