It isn't abnormal to outgrow current positions, teams, or even companies as time goes on. Not only do we change as individuals (we grow up, want different things in life, start families, etc.), but companies also change (they hire more people, pivot, reorg, etc.).
To me, staying passionate and excited about the work you do is simply following what excites you. It's easy to feel more constrained than you actually are. You don't need to follow the management track at your company at all. You can be an IC forever. You can also find a new team, or a new company! You can be a consultant and chose which companies/projects to work with/on (and only choose the ones that genuinely give you goosebumps, they're that exciting!). You can, as you mentioned, transition into new fields/industries.
Your career doesn't have to be linear. I went to grad school to get my PhD in Neuroscience because I thought I wanted to be an academic professor. Two years in, I dropped out because, even though it was intellectually challenging, it didn't fan my flames. (I felt so trapped and uninspired.) I then worked as an operations manager at a startup called Homejoy. It was there where I realized how powerful coding was. After Homejoy, at 26yo, I learned to code. For two years, I did freelance web development and then almost exactly one year ago today, I started working on a side project that very quickly became the only thing I wanted to work on. I'm now a founder of a company (Key Values) and every single day I'm doing something that's new, challenging, and exciting to me.
>>> How do you know when it's time to be okay with [...] trying something radically different?
You should always be okay with trying something radically different (ie. don't be afraid). Maybe the real question is when do you pull the trigger?
It helps to first know what your personal values are, and then you can ask yourself: "Are my behaviors in alignment with my values?" If the answer is no, it's time to make a change!
If you ask me, you should be excited / stimulated / challenged / inspired every single day. We have a pretty limited amount of time on planet earth, so it's really on us to make the very most of it.