I think I've very average - 6" fully erect. My wife of 46 years has never had another dick and I've never had another pussy.
Now both in our late 60s, PIV is somewhat uncomfortable for her even with lots of lube
Therefore, sex these days is primarily hand jobs and oral. She's great at oral, although she refuses to swallow. I think if I was any bigger, she'd be less enthusiastic about oral. if I was smaller, I doubt that would increase the frequency of blowjobs. LOL.
We all need to acknowledge that genetics play a huge role in the development of our bodies, resistance to diseases and the aging process, etc. We've got what we've got and really can't change that. I'll be 70 next month and still have a good head of hair. I wouldn't trade another inch of dick for hair loss.