I mean “warming up” a community intentionally.

For example, one of the subs I regularly read on reddit is /r/audiobooks, looking for recommendations et cetera. The audiobook communities here are dead.

If I want to adopt one of those dead communities here, I could just decide to make several posts a week for a few months. Thereafter, if I’m still keen, and still haven’t had any interaction from the existing mods, I could approach the admin of that instance and make my case for being appointed as a mod.