Tranquility is a real trait that some people have. It’s not a common one.
For most people, a prerequisite feeling for tranquility, is contentment.
And trust me, no pacifist is “content” with the current state of the world. “Worry-free” is literally in the first sentence on the wikipedia page of the word, and I don’t think anyone can be that, except temporarily and/or by being inebriated.
The only way I know to be tranquil, is to ignore the world, and willfully focus only on the good things in my immediate surroundings, in my life specifically.
Essentially, to get there I have to take a break from caring about most things. I don’t like doing that. I want to improve things, and to do that I have to care about things to begin with.
If you had to be content with the state of the world before feeling tranquil, nobody would ever feel tranquil.
And those people are not necessarily pacifists. The issue is that the idea that you would get from movies and TV is that they are one and the same.