Advancing your career can be done with a PKM system. For example, you might be entering some field. A few good things to keep track of: the field itself, relationships, and the different aspects of working in the field.
If you are entering something like Software Engineering, you’d want to keep track of new technologies, trends, etc. You’d also want to keep some kind of CRM, but for your own life. Then there are your notes on the various technologies, principles, processes, and such. And, of course, SWE is pretty broad, so you’d also want to keep tabs on your sub-niche. Say you’re a SWE for a hedge-fund—then you’d want to understand that well, too.
Likewise if you wish to be a content creator. You’d want to keep track of the movements in your niche, the niche itself, other creators, content creation in general, content creation like you do it (video creation, writing, etc.).
The same can be said for other aspects of your life. If you want to become more healthy, there are obviously a few improvements that are common sense. However, past those, you’d want to start managing the vast information in the space. You’d also want some kind of way to keep track of the experiments you run, as well as the results of those—any you do experiment, for any change is an experiment, whether you document it or not.
The most important feature of your notes is their ability to facilitate your thinking (Writing is Thinking). The quality of your thinking—and further, the quality of your decisions—determine your outcomes. As such, you’d want to try to make the best decisions you can: this is what notes can help you do, by facilitating thinking through writing, and by acting as a compounding storage of ideas.