I guess I'm talking about start ups that went from 10s of employees to 100s or 1000s. In those cases I see lots of young engineers leading teams.

E.g. when I interviewed at Robinhood in 2020 one interviewer was already an eng manager after she graduated from school and joined Robinhood just 1.5 or 2 years before. I don't think that happens now at Google or Facebook or Apple.