Highly debatable. When I was in school (mid 20s, so roughly a decade ago, right when smartphones were getting big), I was more tech-savvy than my parents and all of the teachers.

Some others were barely able to install apps and be able to tell what's collecting your data vs what's properly secure, while I was already installing custom roms and de-googling my devices. So I wouldn't say don't give your kid a phone as a blanket statement, but if you do, make sure they know how to properly handle it.