I found an instagram page/youtube channel where a man is discussing assaulting someone and exposing them to CSAM. Who do I go to about this/what info do i collect/how do I go about finding authorities?

Location: California(?)
There is an instagram page that occasionally pops up in my feed. It’s always almost no views no likes. I had never really listened to him because it was always difficult to make out what he’s saying or it was very random or somewhat incoherent. However one video he discusses exposing someone to rape, child pornography, and even what sounds like other forms of abuse. It’s pretty shocking and he is unwell.
In the beginning of every video he gives a full first and last name and I was able to find a website of his. It’s deeply concerning videos. Some other videos discuss his dad trying to kill him or him trying to kill his dad?
Just very frank and unnerving videos of him monologuing. I wasn’t sure where else to ask about this or where to consult about this.

Any help is appreciated