Hi! I really want to change the exterior of my farmhouse (similar to Baba Yaga's house found in the maze on Spirit's Eve but to the dimensions of the 1st house upgrade). I don't have any modding experience so I'm a little lost. Is it possible to change the exterior of only my current farmhouse using content patcher and .json and .png files?
It certainly is! If you look on Nexus mods there are a lot of farmhouse exterior reskins, although I don't remember seeing one like you're considering. Also, all 3 versions of the farmhouse are the same size; and they all live on the same tilesheet (you can change only one, if that's what you want).
If you want a reference for positioning, this mod uses the Baba Yaga house as the 2nd upgrade, sans feet.