If you've not heard of it, MCA completely revamps villagers into making them feel more like people. You can chat to them, improve your relationship with both them and their village, joke, even marry them and have kids!
MCA in 1.21.1 also allows you to create and manage your own villages. Using a "Blueprint" you can manage the town you're in. This means you can add/remove buildings etc.
Adding new buildings is not done through a button however - you need to build a valid room with a door, which then has the required objects for it to classify as a certain building. For example, you can build anything into a storage as long as it has:
Door/Roof
4 Chests
1 Lectern
Players can create their own shops! Crafting a shop allows you to buy and sell items. I highly recommend organizing a shopping district between your neighbouring villages - you will definitely need it. There's no E-Bay in Pig Valley!
We are no longer forcing the economy to be a specific item, nor a virtual bank account - make it be poisonous potatoes or nether star backed securities for all I care, as long as people use your shops then you're good!
On the world map (M), you can drag a rectangle using right click in order to claim an area surrounding you. You may then select an area you claimed again in order to enable chunk loading!
Note: You have a limit on the number of chunks you are allowed to chunkload at any one time. Choose wisely.