It sounds like she’s dysregulated and doesn’t yet have the skills or manage that or to manage not knowing what to expect. Start talking to her a couple days in advance of something new. Explain what it’s like there, who she’ll meet, what she’ll see, what she’ll do.
The key to resolving behavior challenges is determining what is trigger them and working on the trigger.
Occupational Therapy can help a great deal with regulation strategies and building tolerance too.
ADDitude Community Moderator, Parenting ADHD Coach, Podcaster & Author, Mom to teen w/ ADHD, LDs, and autism