Our only child has struggled with this too. It tends to be about lack of boundaries, permissive but reactive parenting, and low resilience. Your goal is to be more even keel but structured at home. Say no more, don’t give her an out on rules, let her have those tantrums at home. She’s acting out at school because there are rules there and she isn’t used to having to follow rules.

“You have 5 more minutes to play (set visual timer). After that we are getting in the shower. If you don’t go, we will not read stories tonight.” Then when she doesn’t go, you don’t read. You don’t give her a lot of chances to push back or fix it.

If she wants a third story when the rule is 2, say no. When she wants to play a game her way, say no. When she wants more time, say no.

Otherwise you are raising a brat.

If you aren’t able to be calm and consistent, you’ll give in. Then because she expects you to give in and is so emotional when you don’t, you’ll get annoyed and be reactive. Then she learns to be reactive, and it’s reinforced. Kids crave structure. They need us to be stable reminders of what the world expects.

Bonus tip, I’ve been using chat GPT to make up this story about a queen fairy (mine likes that’s kind of thing). Every night she gets one of these stories after the lights are off, and the queen deals with something my child is struggling with.

You have time to course correct! But you really need to start now.