theautismfactor.com/meltdowns-vs-temper-tantrums/
Try that. A good number of children on the autism spectrum have 'meltdowns', but they're not the same as a standard tantrum. That's how to tell the difference between the two things. Many of us don't have meltdowns at all - we tend to have 'shutdowns' where we just stop communicating, whilst our brain wiring is cooling down enough to work again.
Either way, if a dc is on the autism spectrum, there's no point in using phrases like, "it makes mummy sad", because that will have no meaning until they get to an age where they learn empathy (and most of us do eventually). Until then, it has to be something that relates to them, e.g. "when you say that, I will take away favourite toy/possession X for Y amount of time and you will go to your room until you are calm", and then do so. It may help to let them wrap themselves in a blanket or sheet - as it helps boost the missing chemical in our brains (oxytocin) in ways we can cope with.
Wait until there is calm. Then explain in pure logic and really short sentences (without eye contact) that the rule is they do not say A or B and they do not do C or D. And put pictures on the wall to show what you mean, e.g. picture of someone kicking or biting or hitting, with a big red X through it to mean 'no'. Pictures often work much much better than words to remind us.
Teach other children in the family to say 'no', hold up a hand to show 'stop' as a signal, and walk calmly away to get an adult. Won't always work, but it's a start. Violence and hurtful words are absolutely not appropriate and we all have to learn not to do it. It just takes us a longer time to get the message and to find other ways to divert ourselves before meltdown happens.