6 ways to expand knowledge apart from reading books
Apply your knowledge. Knowing is never enough. More you apply better you get.
Make notes from books. Revise like exams. One reading is never enough. Every time I reread any book, I get a new insight. We pick only those things which are necessary for our immediate survival. As life progresses our challenges change and hence we need better insight.
Activity and traveling are always helpful in getting more practical knowledge.
Writing your thoughts out always helps. Introspection is viable only when you reread your thoughts. Metacognition (Thinking about thinking) is also best while rereading your thoughts.
Teaching is known to increase your skill in any discipline.
Cross Mixing of ideas helps to reach higher goals. You can do mixed learning. Learn new topic, subjects, disciplines etc.
Your mind is 10X more creative than you assume.