Most of the problem with windows is they need to meet egress code if they’re in a bedroom. With today’s construction practices once you have built the wall, installed the 2x10 header under the top plates, rough out the opening for an egress window and install it, it is usually 18-20 inches from the finished floor. I would have to check my code book but in this instance life safety code would take presidence over residential code.
Next time you drive around a new sub division look at the windows, you’ll see most houses built today the windows are all the same size, this is so all the window in the house meet egress code and the MFG just mass produces them so they are now a stock item and cheaper for the builder.
This poses a problem when remodeling an older home, in most older homes the second floor windows are usually the same width but smaller in height than the first floor windows. If you where to build a full dormer on a 50 year old cape you would need to install egress windows on the second floor for the bedrooms to meet code. This would make all the second floor window larger and unproportionate to the first floor windows and closer to the floor, which by the way is unsafe for small children. The best way to solve this problem is to install casement windows on the second floor that have special egress hardware which allows them to open a full 90 degrees thus meeting code.