When you save a window state, Breeze remembers the relative size and position of the focused window.
At any point, you can apply that state (size and position) like a template to any other focused window.
Breeze comes with some handy default window states for Fullscreen and Splitscreen Left or Right.
Updated on Aug 19 2019
Note: The downloadable demo is version 1.5.11; the version available for purchase on the Mac App Store is version 1.6.