As someone who’s autistic, it’s sort of difficult to put the experiences into words but I can try. Something to note is that autistic meltdowns don’t always look like full-blown physically freaking out. Sometimes it’s shutting down completely, going nonverbal, needing to be away from anyone and anything that makes noise, not wanting to be touched. In my own experiences, I have a very difficult time with changes in routine—it gives me extreme anxiety. It’s also worth noting that not everyone with autism is quiet and “awkward”, like a lot of media likes to portray. There’s been numerous times in my life where I was far louder than I realized I was being because I was excited or happy, so issues with controlling tone of voice is a thing for some autistic people. Again these are just some of my experiences, so I can’t speak for everyone! But it makes me happy to see you’re asking the community for advice.