Will Beemer’s book is exactly that. Gives full plans plus some variations for a 12x16ft. We used it to build our cabin and it was great (also took a class with him!).
Learn to Timber Frame: Craftsmanship, Simplicity, Timeless Beauty
It has a set of plans with variations on size and modular expansions to fit your needs
You might be interested in this. I've been thinking of building a barn with hand tools and logs.