One way to demonstrate platform reach to an agent or publisher is to demonstrate real-world reach. Many local newspapers accept freelance writers to help tell the news. Even ones that do not will often jump on a well-written press release.

Be it by press release or freelance writing, make a point of getting published in your local press. Add clippings or links to a page or section on your website. This will demonstrate that you have reach beyond a Twitter account and an Instagram account. Showing that you know how to reach the people where you live will increase agent or publisher confidence in your author platform.