He is 5. He's been showing aggression towards his younger sibling. He'll take toys away, growl, and push his sibling. We've talked to him multiple times about how he doesn't see that behavior from us and he shouldn't be doing those things. We tell him to use kind words and let us know if he needs help with his sibling (if he wants something from his sibling). We give him praise and encouragement when he tells us he needs help, uses kind words, shares or does something good towards others. We've taken away screen time, favorite toys, and sent him to time out. We're trying to work on sharing feelings and thoughts with us. He'll get emotional and shut down. He has started hitting students in class. The teacher has talked with him multiple times about his behavior. I feel like we can't get through to him no matter what we try. It makes my heart sad because he's going through something but can't express is through words. Please help.