Giants appear in most mythologies. For example :- The giants of Jotunheim, David and Goliath, The Titans to name few.
But I don't recall any specific myths to do with growing physically, spiritually yes, most hero's tales were.
My only theory (and it'll be a bit of a ramble so bare with me) is that gods/hero's had all their defining traits amplified. For example the idea of a perfect male in the past would have been strong, tall and physically capable. Over time those traits were quite literally made bigger too, I suppose due to fantasizing or exaggeration of the stories and then you end up with a 13ft guy who can shot lightning from his hands.
While I have no proof, I believe that certain people would have fantasized about being those Heros/Gods with all the strength and size that went with it no doubt in a state of arousal.
I'd love to hear other people's views on this. I also have further theories but I'll save those for later when my brain wakes up a bit more. Quite an interesting post GB😃