"Out of the mouths of babes..." we like to say.(Here's one of Zach's from many years ago.)
However, whatever wisdom is expressed by children typically comes from their complete innocence.
That is, the wisdom does not reside in the child speaking, but rather in the adult who hears the speaking.
(Corollary: if a child utters some astute observation and no-one hears it, it probably ain't a wisdom!)
The wisdom of an adolescent is a bit different. It is a quirky blend of innocence and emergent wisdom. Here's some examples from Zach.