For new parents RLI1105, it's hard to say because there are so many factors some sociocultural, some biological which the former might exasperate - there is still a lot to learn about puberty and brain development, but there is a lot of writing on puberty itself as a factor, that likely teenagers have a wider range of emotions and more difficulty coping with them (middle age might also be a factor with the whole U-bend of happiness effect). We may never know them all.
Having been the mentally ill kid and now having children myself, I think one of the most important things is teaching coping skills, having space to practice - and fail at and know that failure can be normal - coping skills, and having emotions normalized even when the response isn't desired.
So, to use a toddler example, many kids tend to hit when feeling a strong emotion. When mine were young, my spouse or I would hold the hand they hit us with and tell them that it's okay to feel [emotion], but it's our job to stop them hurting anyone (including themselves) until they can do it themselves. And we would hold until they calmed down. It took time, but they stopped and I continue to frame similar things as helping until they can do it themselves or cope themselves.
After some bumps with my oldest, we blocked web browsers - at his request - because he couldn't cope with managing it even with the family filters and all on. We actually attached a computer to our TV and used a usb keyboard so when they used it, it was in full view and we could talk through everything together. I treat the internet like going out, first with my holding their hand, then walking by their side, then walking with them, and so on. I think this helped.
Also, a mistake I made, is seeing a behaviour and using pathological language. I did that with my DD1 - she was talking about a habit she does of pacing in her room while daydreaming and it caught me off guard as I did that when I was young & I called it maladaptive daydreaming in the discussion, because that's what many call it when it's attached to a disorder like I have, but it's also a perfectly normal behaviour. I had to walk it back with her, repeatedly, because she heard 'something's wrong with you' and she was at an age with some peers where it was mental ill health oneupmanship (which has thankfully started to fade as they've gotten to the end of Y10, though part of it was shifting social group)
Social groups are very important, and I never said she couldn't be friends with people, but I always reframed when certain friends got very absolute about something and taught her to focus on those people who help her feel good and spend less time on those that made her feel worse.
I had a lot of adults treat me like a freak, but what helped me most were those adults who didn't take BS or excuses, but also gave space and talked to me enough to find out what was going on under my abnormal behaviour and gave me scaffolding and hope that I could learn to cope better and that even when my reactions were weird or plain wrong, my emotions - including my anger - weren't. It's normal to feel angry when betrayed or let down, but there are ways through that (Emotional First Aid is a good TedTalk/book on this).
One important emotional skill is knowing emotions are another type of sensory information, they tell us something, but we might not always know what (just like we don't always recognize what's causing a smell) and they pass, it won't smell like poo forever and it'll smell like it less and faster doing certain actions though might not keep it away forever.