Well, there are a few communities automatically listing new communities and growing communities. Some people have an eye on them, or scroll through the All feed. They might notice on their own. Example: !trendingcommunities@feddit.nl

But you need some good content in your community for people to want to subscribe to you. If it looks empty or has maybe one post… It won’t attract people.

So foster your community and add some content. Do that regularly for some time.

What also helps is crossposting.

And you might want to engage in communities like !fedigrow@lemm.ee