Can I call CPS anonymously for a wellness check?

I worry about my little brother. It’s something that breaks my heart.

He lives in a rural town with my mom and her husband. My other siblings and I lived with them from 2005-2010 ish. He was emotionally, verbally, and physically abusive to all of us. He would use us as pawns to try and pit us against each other. My mom is a textbook narcissist and got pregnant to trap her husband. She also has a strong victim mentality and blames us for abandoning her when we left her house. Her husband kicked out my older brother and sister and they were the ones taking me to school and basically parenting me. My sister and I both have anxiety, I have ptsd, and my brother has anger issues. I firmly believe it is due to what we went through as children.

My brother is the only one who lives with them. They are incredibly controlling of what he is allowed to do, watch, or play. He isn’t allowed to play Pokémon, but he has to listen to his parents argue and his dad call is mom a fat bitch, piece of shit, etc. He has developed pretty bad anxiety and has meltdowns at school over tests. The thing that scares me the most is that he is all by himself. And his parents have the power to create a very bad person, or severe mental illnesses. At least when I was going though it I had my other siblings. My mom lives far away and rarely comes to town and when she does it’s only to get groceries and go straight home.

I really want a wellness check for my brother. I want him to be able to talk to someone without being scared of being in trouble. I know if they knew I called CPS they would never let me be around him again. I already have such little contact with him because of his parents.

What can I do?