I think I recall seeing one of the Sketchup team’s Live Modelling sessions about using SubD for just such a purpose, or one very like it.
Let me see if i can find it…
Sorry, I can’t.
But I did find a reference to one going back to 2017 by TheOnlyAaron. Try the Sketchup Facebook site and see if you can find it there.
I did find one about using SubD, but it was for contoured cars, not humans.
A second more targeted search on this forum found this: