I’m not exactly sure I fully understand what you mean.
If you simply want to create a WPSP that displays posts from specific Author, you can do that by specifying the Author ID on WPSP List setting’s “Most settings” tab. https://share.getcloudapp.com/jkuYbxpn
But if what you’re looking for is some sort of AJAX search functionality included, I’m afraid you’ll have to get a plugin that does that specifically.