Do you mean the Webfinger plugin?
I'm not completely sure on how necessary it is, I am not a developer. Sorry 😞
Accounts only show up on Mastodon searches if someone on that server is following them, or if they have been interacted with by someone on your server.
So, if you want to get your blog noticed in searches it's a good idea to tell people on Mastodon etc its address and encourage them to follow the blog.