If you want to bring new villagers to your island, then you need to expel some villagers first, MMOAH will tell you how to remove them.
How to remove villagers?
In ACNH, there are several different ways of expelling villagers, we will list them all.
An old-fashioned way to remove villagers
A thought bubble will appear over the head of the villager who wants to move out and you will notice this. If there is enough time, the villagers will move out on their own. But time travel is a better option, it will speed up the process, which will only take you 15 days.
At the start of Day 15, the game will initiate Isabelle's 5 am broadcast, and the villagers to move are randomly selected. If the correct villager has the bubble on their head, you can let them leave your island. But if there are no bubbles, you can always dial back a few minutes before Isabelle broadcasts and check again.
Remove villagers with a Camper
You can build your camp, possibly using the villager you want as an amiibo. If you have the latter, it can invite the villager to the campsite via the Nook Terminal in Resident Services.
Once a villager appears in the camp, you need to talk to the Camper for 3 days and possibly win a game to convince them to move to your island. The Camper will randomly choose an existing villager to replace, and they will tell you. If they choose the wrong villager, you can reset the game and restart the conversation until they choose the right villager.
Now you can remove villagers according to the above ways. If you have a favorite villager, you can come to MMOAH to buy ACNH Items, which will make your favorite villagers appear on your island faster.