No. I have a friend that’s 5’2” and has an 8’ x 5.75” and one that’s 6’3” that has a 6” x 4.5” erect penis. I have seen more naked dudes in my life than I really ever wanted to during my time in the military and can honestly say there is no way to guestimate anything. There’s big,small,fat,skinny, etc,etc on every build, height,race, etc.
I’ve seen atleast half a dozen, in my lifetime military time and working the prison system for a bit, that were a good, no exaggeration, 7-8” flaccid. All of those were on skinny (150lb or under & under 6’) white guys, with the exception of one Peurto Rican bodybuilder who had the girth to match the length!
I worked with one old dude (maybe 5’7” 140-150lbs) back in the day that wore bib overalls and would pull his dick out of the side of them to piss. I know, I’ve seen him do it. Huge penis’ aren’t myths, they are granted - rare, but do exist.
I’ve seen short guys with 6” flaccids and ftall lean guys that looked like mushrooms in turtle necks. I seen one dude in the showers once that was like 5’ tops and although not excessively long, he was probably sporting a 6” flaccid girth.
You just never know!