I found !ttrpg.network (not sure how to link from kbin, but that's what i search for) and it seems to have a lot of good, active communities. Other than that, I haven't found anything more populated.
@EmpeRohr Off the Fediverse, dndbeyond.com and 5esrd.com are actually more than sufficient to get someone started. I do recommend trying to get either the starter or essential's kit because you'll also get the digital version on dndbeyond.