Site-built “bays” add space to a room because the floor actually extends into the bay. This allows a person to stand in the bay and enjoy an expanded view.
When planning a bay, it is important to consider how the windows will appear. Shall they be UNITED? or DIVIDED?
If siding will divide the windows, then any number of window sizes might work in the wall space.
With some planning the windows can fill the space and trim boards can connect the windows. This method helps them appear as a group rather than separate individual windows.