This is a good question and I will answer it a couple ways. My first thought was to suggest the Assemetry lesson as a good time to significantly change the face’s shape if desired. You could contain such modification non-destructively in a shapekey to be turned off if needed.
But that only addresses the shape of the face which is not the only thing that makes faces unique from each other. Everything from skin tones to hair to eye-color to blemishes also affects the uniqueness of a face. So a better, more thorough answer would be to create 2 portraits: One like the face in the course and a follow-up that’s unique.
Use the first portrait to really nail down the concepts and workflow. Then a second portrait does two things: 1) it puts you’re learned/mimicked skills to the test and 2) presents an opportunity to create an entirely unique face in terms of shape, skin tone, hair, etc.
I recommend students do multiple portraits anyway because there’s way too many concepts and skills to learn perfectly through one viewing and one resulting portrait. A second (and third, fourth, etc) is what will establish and refine these skills long term.
