There is no one, or right way to approach any of this.
I don’t think the guy who gets hired to be the armor maker set out to be “the armor maker”. I am sure that can happen. But mostly it is just happenstance. You start working on something because you want to get good at it. Somehow, someone finds out you can do that, and they hire you. And then one thing leads to another. Next thing you know you are full time making helicopters for a year. The only way out of that is to manage your time and keep learning to do other things. Because either of three things are going to happen. You are going to burn out on making aircraft, aircraft jobs will dry up, or you are going to find yourself in need of work with nothing in your portfolio but aircraft. And you will loose out on all of the jobs because no one can believe you can do anything else.
The one thing to remember. Especially in the beginning is that you make your future based on what you do now. So if you really want to diversify make that plan now. And do a wide range of things really well. But one by one, if possible to really nail it. If on that journey you wind up being hired to do the first thing you mastered, then make plans to keep learning and add to your portfolio so you can have more options to get hired down the way, and also keep your interest in the game as you go through the years.