The are three important stages for new aircraft design
Do you start with a blank piece of paper?
Probably you have some requirements!
Then, do you start with a blank piece of paper
Probably not - you will include statistical survey of existing aircrafts in this category and develop some ideas on
W, S, b, c, cruise altitude, specific fuel consumption, CD0, etc.
You can iterate on these design values until you fix your final values for W, S, b, c etc.
Start the preliminary layout - 3 views
Generate wind tunnel model, CFD calculations , control surfaces
Lots of people designing lots of parts in CAD