It can be normal, but it's worth keeping an eye on.
12-year-olds might be "big," but that's not the same as "grown" or "mature." My daughter, now almost 14, has had a rough time in middle school. Every couple of weeks there's enough wrong that she just sobs about it, completely inconsolable, for ten minutes straight. Something like: she's hungry, and tired, and there's a lot of homework, and somebody said something rude about her favorite shirt, and then I told her to wash the dishes... and suddenly she's screaming into a pillow about how horrible everything is. (The most recent trigger is a household chore, but me nagging is not the only problem getting her down.) But after flipping out, she's better. Not great, the dishes get done with plenty of grumbling, eye-rolling, and clatter -- but she does the dishes, eats a snack, texts a friend who will say how awesome that shirt actually is, and gets back to her "normal" self.
I'm not saying this is a great method of handling stress on her part ;) But sometimes she is just overwhelmed and needs an immediate outlet for all the negativity in her head. Since she's a child, screaming and crying are an easy way to release it. It's also more likely to happen around me, because I'm safe: I won't judge her or be angry the same way peers or teachers might, I'll love her no matter what and I will respond with helpful concern.
We have worked on, and continue working on, finding healthier stress outlets both long-term (getting enough sleep, exercising, eating well) and short-term (discussing good reactions in high-stress situations: "if I ask you to do the dishes but you're really overwhelmed, how can you tell me that? how can I balance giving you time to decompress with the fact that the sink is full?").
That being said, a tantrum and a panic attack can look awfully similar. If the events that trigger a "tantrum" are very frequent, if it seems like she legitimately can't get control of her crying, or if you've just got a gut feeling that this is a more extreme reaction than a pre-teen should have -- talk to your pediatrician at their regular annual exam. They can help ask your daughter(s) questions about stress, triggers, reactions, and general emotional state to tease out whether this is just poor handling of an overwhelming day, or a pattern of anxiety, stress, depression, or even emotionally abusive "friends." And then you, your daughters, and their doctor will be able to decide whether more professional intervention is required. (My daughter regularly sees a therapist, which gives her an outlet to talk, a professional resource to suggest coping techniques, and an unbiased judge of her perspectives. It's helped.)
I'll also side-note that a friend that teases a lot, especially if they're aware it is causing pain, isn't a great friend. I tease and am teased by my friends, but we're conscious of each other's limits. If feelings get hurt accidentally, we apologize immediately. Anybody that doesn't have the same consideration for my boundaries is definitely not fun (or healthy) for me to hang out with. From experience, this is hard to teach to pre-teens, and they are likely to take even gentle teasing a lot more personally and deeply than a grownup. Acknowledge how much it can hurt feelings before you tell them to just ignore it -- the pain legitimately exists, even if they don't need to be letting it get to them!
