For general advice on modding, see Using other mods with Horizon. Located on the third floor of the building on the left before reaching Preston Search for Sim Settlements, then press A and select Download.
One of the first addons for Sim Settlements 2 is the Junk Town update which adds twenty-eight new homes, seven new shops or businesses, six industrial factories, twelve different farm plots, eleven new martial plots, five municipal areas, and twelve recreational zones. Like many Bethesda Softworks games, Fallout 4 has hundreds of mods available to fix bugs, enhance gameplay, or let you do downright silly things like put anime characters into the game.