Read a lot of books. Meditate about deep subjects. Talk to a lot of people smarter than you. Study philosophy. Align your desire to be smarter with your lifestyle. (Just reading some interesting threads in this forum expands your consciousness)
They each will have their own way of bringing a lot more complexity to your thought patterns. I myself am attempting to bring more complexity to mine as well.
It’s been one of my biggest goals for the past few years.
Probably would recommend reading Atomic Habits, because habits can help you have higher level thinking patterns like meditation which was brought up earlier. Book may lowkey change how you operate forever.