In the story there are major structures that have to be built to specifications (and plenty of minor ones early on), though for the major ones you just have to supply materials and villagers will complete them for you if you don’t feel like trying to match a huge blueprint block by block. There are other parts of the game where you have lots of leeway and get general requests for things like a certain type of kitchen or bedroom that tell you what furniture and decorations are needed to create that room, but it’s up to you to build it as large or small as you want and embellish it and you can use any type of blocks you want for the walls and flooring if you’ve got a preferred aesthetic in mind. There are also whole islands where it’s just free form build whatever you like. At the end game you can buy materials instead of gathering them yourself if you want and just build to your heart’s content. You also get some better building tools as the story progresses.