Regardless of if she is ND I would deal with it the same way. If my nd child hit me or a sibling I would ban all screens for the rest of the day if it's the morning or for tomorrow too if it were the afternoon. Possibly if sent to their room for 5 mins instead if I could see it was triggered but i have a saying "it's a reason not an excuse". I would have been watching for triggers and tried to mitigate- you need to think very hard about what was happening before these behaviours. Not just what's happening but also the environment. If you are dealing with ND then be aware supermarkets are sensory hell.
Don't ban tv but allow the iPad. It's not a punishment if they can switch to something else of equal value to them.
Praise your son for good behaviour and reward that good behaviour in front of dd. Do not give in to the inevitable meltdown she has when she doesn't get the treat.
Star charts are not great if it's emotional regulation that is the problem. You need to reward/consequences in the moment. And you need to massively praise her communication of things that wind her up.
Stop spoiling her with tech and sweets. Spoil her with quality time. Quality time both with and without her siblings. I'm currently on holiday with someone who keeps buying my nd child treats and spoiling him and I've had firm words as it turns him into a right brat when he gets stuff for nothing.
Consider diet. There is a red dye that send my child loopy so I avoid all red processed food and sugar and sweets. Massive difference.
Give more warning for transitions. 10 minutes 5 2 then 1.
I recommend starting to use the word 'consequence' that way when you say right that's time to go and she kicks off you can say do I have to give you a consequence or can we work together to not get in trouble? (Always offer to help her avoid kicking off). If you say consequence then you can change the consequences depending on situation/severity of behaviour.
Consider if she has too much screen time. I know people say screens are regulating for ND kids but that's not true for all amd it's certainly not true for NT kids. If my nd kiddo has too much screens he's a brat. I've banned Roblox that game has horrible impacts on behaviour in so many kids.
Don't let her get away with bad behaviour and excuse it as she may be nd but don't dismiss nd. I'm nd and was diagnosed as an adult- my mother thought I was a brat (I wasn't actually that bad) but being punished for things I couldn't control and getting no understanding or support to help me work on those lacking skills has left a lot of damage. Obviously you haven't said you tell her she's a brat but my mother said this to me and I've never forgotten and I will never forgive her. I tell my kids their behaviour is unacceptable, Ive said you are being horrible and things like that but always follow it up with "and I know that's not who you are and you can do better". If a kid thinks you think they are naughty then that's what they will be.
And try not to be embarrassed. Your dd may be acting out but in that moment she is really struggling and she needs you focused on her not embarrassed about onlookers. That focus may be discipline but it's still a need and you need to worry about that and not what others are thinking.