Wow. We got my daughter a flip phone when she was 14 - so she could call us if she needed us. Because public phones were disappearing and we didn’t want her to have to depend on a friend - in case she was in a friend situation that was making her uncomfortable (we always told her we would call her back and tell her she had to come home so she could complain and then leave.)
Dgs, age 2, is allowed to hold the phone during family video calls with relatives.
I can’t imagine handing an iPhone to a 6 y.o. - here kid, unsupervised access to the entire world. Have fun.