I’ve got a different take on this than you’ll probably hear from others. You’ve got to make a lot of mistakes, but more importantly, you have to learn from them. You need to live with your choices long enough to learn how good or bad they were and in what ways. For bonus points you can acquire the skill to learn from the mistakes other people make without being judgmental.

I dont have a really straight-forward answer to this, but for me I find that trying out different ways of doing things helps me feel like im growing as a developer.

This could be trying new languages, methods,etc. But also going over ground you’ve already covered to see how you would do things differently if you had to do it again.

This is probably not the industry definition of a "senior"role but in my personal definition you need to become a good leader. Whether its an appointed position or an unofficial role, i feel like all senior roles need to be leaders in their teams. Being a good leader has many facets, but one i’m really drawn too is teaching others. This helps you build your mastery of the topic but also helps to build up the others on the team.

From a technical skills perspective, i have found that there is no substitute for just building things to improve your skills. For me, the act of building something (even if its a “toy”) will lead me to seek out the good libraries, books, videos, etc that are out there.

Sorry this was a very non-specific answer. I figured tons of folks will probably share their specific technical resources. I wanted to share my take on this.

Good luck in your journey!