You overreacted mom, sorry. It's what we do sometimes when we're angry and frustrated.
A kiddo of 5 has very little concept of this consequence and she has no way of making a connection between having a temper tantrum has to do with going to a festival. That was not a natural consequence. Ignoring her and letting her wear herself out would have been my choice.
Think of it like this. When you get mad you have a filter that keeps you acting in line, it reminds you that acting out is not the best choice, to use your words, discuss what is wrong, etc...
A 5 year old is not able to think like that at a good calm moment. If they're having a temper tantrum they aren't even using their higher brain function, they're in their brain stem and are just a little reactor, not able to comprehend what is going on around them much less decide to stop releasing all the anger and frustration and just sit there all nice and quiet. They are reacting and not able to process thought.
I would have let her stay in her room and kick and scream all she wanted. It would have served 2 purposes. She'd have gotten all the anger and stuff out of her system and felt better plus she would have probably fallen asleep.
The other part she would have learned is she got NO reinforcement during this tantrum. By going in and interacting with her you were reinforcing the tantrum. She kept going because she knew you would react and come in and give her attention, it wasn't a good interaction but it was attention.
So, go to the festival, you overreacted. Have a talk about how someone who is angry can make bad choices. Talk about how you felt angry and didn't make a good choice. Help her to learn that even adults make mistakes.
If you have to be involved in her temper tantrums because she's at risk for harming herself or property here's a good way to teach her how to calm herself.
Hold her in your lap, you can use holds if you are at risk of getting hurt but if she's just wiggling around and not kicking or trying to hit you then sitting her facing away from you with your arm around her waist should be enough.
I hold my grandson on my left knee facing away from me. I put my left hand under his left arm and I hold his right hand in my left hand. I basically have him immobile at this point. He can kick and scream and try to head butt me but isn't going to be successful.
So he's sitting in my left leg/knee facing out and is in a safety hold where he can't get away or get hurt or hurt me.
I then put my right hand between his head and my face. I don't want another broken tooth or bloody mouth. I use this hand to rub his shoulders, neck, and arms. I use calming language and gently remind him to take turtle breaths. That's a slow breath. If he tries to bow back and head butt me I have my hand between us and he only hits it and not my face. He can have a tantrum as long as he needs to this way.
He calms down now in just a few minutes. Even when we're out in public I can do this. No one sees me doing anything that is incorrect because I am helping him calm down not punishing him. I'm teaching him to breath and relax his shoulders and muscles. He has learned to do this almost as soon as I put him in my lap.
Using relaxation techniques you can teach your daughter to relax and focus. You can help her learn to release the frustration and anger out and have more control over herself. BUT this will take a long time. She is a little kid and has a lot of life to learn how to manage her emotions.
If he's having a regular tantrum and not destroying property he is welcome to kick and scream and cry for as long as he needs to. If he was kicking the wall or door and it wasn't hurting it I would let him continue.
Sweet Chaos is right, I had forgotten about that option. We did take the bedroom door off one time and our oldest grandson had to earn it back. He got caught watching adult swim on the TV after the cartoon channel stuff went off. He said he'd fallen asleep with his TV on and wan't watching it. I heard him laugh and that's why I opened his door in the first place....