While I don't maximize anything on a monitor that wide, I do appreciate Window's snap to half/quarter functionality for monitors that wide, and I wish Mac had the same ability natively.
Hover over the green button in the top left of the window. I recently found out about that menu for moving a window between screens, which is also an option it has. (I also just found them in the Window menu if you prefer that. I dont; the options take an extra level of hovering to get to.)
Weirdly it still doesn't quite do what I want. It leaves a gap around the edge of the window for some reason.