If you are using social stories then create photos of her or the situation around that is the issue. Photos of the other children doing things so that she can understand.
You can create social stories with a range of things, we do have a app that will do what you need that you can create with photos as well as print and update appropriately https://www.specialiapps.org/en/special-stories-plus
If you have any professionals supporting, you can ask their input or you do have a friendly Speech Therapist or Educational Psychologist. then you could ask for recommendations.
It’s hard to say what language to use without knowing more, put it may be create little stories with the there children first so that she understands what is going on and what she is missing, but you could create stories that show the behaviour you want her to do
Susie is playing outside.
Mrs White rings the bell.
‘Time for lunch!’ she shouts.
Susie lines up with the children.
The children walk into school.
Susie takes her coat off.
The children walk to the dining room.
Sues eats her packed lunch.
Or use visual time tables which could be photos, or symbols – keep it simple as it may be just going back to just simple instructions or visual prompts
I agree with whats been said earlier as language is important to phrase so it’s an instruction not request asking her permission, visual timetables and getting her involved, rewards all those type of things
She needs the role model on how to behave may need a reward system
There are some parenting tips for toddlers you can look at https://www.verywellfamily.com/parenting-an-oppositional-child-2764635 as it may be something she grows out of or may get worse and become a problem and you may get some ideas from searching parenting advice if you are working with the family as well as in school as a shared strategy would be be better for her as she is getting clear guidance from all adults.