What would you do if your child was being severely bullied

So this is a discussion that needs to be had because bullying is a thing that happens on a daily basis everywhere. I don’t care what school it is, bullying happens. So we need to, um, find ways that we can have our children be able to cope in their situation. But I really want to know what you would do as a parent. If your child was being available.
https://bullyproofkids.org/what-would-you-do-if-your-child-was-being-severely-bullied/