I would not label this control - more like they gain experience in recognizing their own feelings, and for that split second after they register and become aware of their feelings, they choose an appropriate response. I remember Obama being heckled at a speech by someone - you could clearly see his irritation by his pause, a second or two of deliberate delay/processing what he felt, and then just gave a somewhat calm response to the person in an effort to defuse the tension in the room.

Trump notoriously sucked at emotional regulation, and he's what you'd consider 'an older individual'. He too would give measured responses, it's just that they were more direct/less diplomatic than say Obama's.

I used to be more knee-jerky in my responses, say 20+ years ago in my 20's, but after a lot of screw ups in life w/relationships (close/intimate ones in particular), a failed marriage, 2 kids and a lot of therapy, both group and individual, I've made progress in being aware of my feelings and responding in a more measured way, so outwardly that appears as if I have "greater control".

The reality is I'm still a mess - I'm just responsible for my mess before I vomit it outward on someone else.

LinkedIn Learning actually has this great one hour or so video I just watched that covers this nicely, I think it's called "Emotional Intelligence"... Some say it predicts how you will fare career wise far more than being just technically adept/skilled.

It's a process of "finding oneself" and figuring out where we fit best. Mastering responses to our emotions is a life long process and we tend to end up "automagically" drawn to similar people, cultures, companies, relationships....