OBLIGATORY PLUG: This community has it's own LFG section. Nobody's posted any game ads there yet, but it's very new. If you're looking to start up or join a game yourself, I might recommend starting there. And while you're there please consider clicking "subscribe" because new folks checking it out are more likely to post games there if they see a bigger number in the sidebar.
I haven't played an in person game of D&D in over fifteen years. The last time I played any sort of TTRPG in person with people gathered around a table was a Werewolf: Dark Ages one shot at a Fourth of July party in (I think) 2010. I had signed up on an interest sheet left at my LGS where I played MTG weekly for a game someone was looking to start up, but this was in March of 2020 and our scheduled first meeting and Session 0 was set for two days after the COVID lockdowns went into effect, closing the LGS and pre-emptively ending that game.
I do play D&D online via VTTs (mostly Roll20 but I've also used Foundry) and have done so regularly for several years now. I found my longest running game, which has been going for about two years now, on a D&D centered Discord server with a LFG channel. Lots of such servers exist and I recommend checking some out (just do a search for "Discord dungeons and dragons" (or a different game if that's what you're looking for). The other long running game I'm in actually spun off of that first one and includes mostly the same people just playing a different campaign on a different day. I also joined a third game that I found on r/lfg but I'm avoiding that right now because of the API bullshit. Did I mention this community has it's own LFG section that works pretty much just like r/lfg but with 100% less u/spez related bullshit? I have also in the past found games, mostly for one shots, on the D&D Beyond and Roll20 forums, both of which have LFG sections that are fairly high traffic.