if you introduce yourself to a villager when they first move in and don’t talk and completely IGNORE them for 1-2 week, they will move. (based on what i’ve experienced) if you build up a friendship then one of their triggers might be to move away. you can’t tell them just to move away.
you'll see them thought bubble, and then you'll have to tell them to leave! as far as i can tell so far, they won't leave unless you do that. unsure if anyone has had a different experience!
i'm enjoying that so far, since it used to make me pretty antsy about taking breaks from the older games!
I find that flat out ignoring them doesn't makes them leave faster/at all. Just speak to them maybe every other day and they'll get the thought bubble above their head and they'll say they're thinking about moving
i tried ignoring villagers for awhile, but i think TTers confirmed that the move-outs seem totally random. my first three move-out requests were the villagers i talked to (and loved!) most! ruby even asked me twice.
According to TT'ers who traveled some 40 years into the future and back, no villager will leave unless they first confirm it with you.
They'll get the thought bubble even if you don't interact with them for over 40 years when they intend to leave so it's not like in NL where villagers would stop pinging you when you didn't play or talk to them for some time.