Too often this happens at the hands of villains: Psylocke from British aristocrat to Asian ninja by the Hand 🤮 , Angel to Archangel by Apocalypse, Bucky to Winter Soldier by Hydra, etc.

It serves to up the angst… “Oh woe is me, I’ve been upgraded…”

The only hero that I can think of that got upgraded by another hero is Spidey’s Iron Spider suit from Tony Stark.

I can’t think of any DC characters this happens to…

Underworld Unleashed was a whole crossover event where Neron used hell powers to upgrade a bunch of DC villains.

What you want to search for is “power augmentation”. Theres a bunch of comics that cover it. Search for that term and you’ll get a few wikis that have more info and examples.

I mean depending on how broadly you look at it its a common thing. In marvel the inhumans and the eternals are races created by extraterrestrial entities and I believe mutation may have an origin like that. Then you have things like wolverine having admamantine bonded to his bones. Mister fantastic making unstable molecules which most heroes use for their costumes so their powers don’t destroy them. This was the origin of the symbiote as spiderman used regular cloth and his costume was getting torn up on the battle planet and the beyonder provided the symbiote as a fix. The symbiote then enhanced his powers. several other tech heroes like stark and pym have provided tech to enhance other heroes although I don’t recall specific instances outside of the spiderman movie but I know it has happened relatively often. Thors powers are enhanced by his hammer and he has had other things come up over time. There is a sorta common thing were a hero loses their power and some technology takes its place. Doctor strange has innate magical ability but also artificats some of which he uses all the time and some temporarily and sometimes he loses access to his usual items.