Supporting 5yo daughter

My 5yo daughter has recently been diagnosed with autism. She’s in her first year of school and is doing very well which we are grateful for but we know she is high-masking. At home she regularly (almost every day) has tantrums that involve screaming and hitting. I wondered if anyone had advice on how to manage this? I feel like we have tried a lot but when she’s having a really bad time it seems like there’s nothing we can do. Her emotional dysregulation rules the house. It’s very sad.