I know this might feel like /r/iamverysmart but I'm self aware enough to know that what I feel is not necessarily the truth. How do I combat this feeling of superiority?
Smart is a spectrum and ego is the enemy if your goal is true greatness. Otherwise you’re just going to be stuck feeling smug that you’re in the 1% when there is this whole other level you could be operating in if you stopped feeling so good about yourself.
There's also the (closely related) illusory superiority effect (i.e. "everyone's an above average driver"): https://en.wikipedia.org/wiki/Illusory_superiority
Consulting disabused me of this mindset pretty quickly. As I took on tasks outside my expertise (e.g. project management, contract negotiation, marketing, devops, etc.), I had direct proof that said expertise was far more limited than I'd realized. I might be good at engineering (and even there, I've gained more of an appreciation for where my skillset starts and ends), but there's a lot I don't know.
Aside from that: talk to people outside your field, and take the time to deeply listen. Nearly everyone I talk to, whether they're a field biologist, a welder, a sommelier, a lawyer, or an art history expert, takes something for granted that I have no idea about. In many cases, I've been surprised by how deep and interesting knowledge outside my field can be, and I've been forced to re-evaluate my earlier belief that engineers are somehow superior to other walks of human life.
For instance: did you know that humans exhibit marked sex differences in olfactory perception? [1] I learned this from a scientifically-minded wine expert on the bus from Montréal to Toronto. That's the kind of thing I'm talking about: people know things you can't imagine.
Too many people try not to feel superior but secretly feel deep down if they tried to prove it they would come out superior, and so they keep a subconscious sense of superiority under a veil of humility.
You will either discover you were not as great as you thought or you actually are the best. There’s no other way.
Similarly, we tend to judge others' intelligence by their achievements, but we judge our own by what we could do.
The antidote is humility. Genuinely and in good faith assume that other people can teach you something. Get out of the habit of asking yes/no questions where you define the premise (except transactional interactions), ask how, what etc. You'll quickly meet people who are smart in domains you barely knew existed.
Then wait until you have kids, and you'll realize how out classed you can be :-)
Whether you think it’s the truth or not, nobody cares. People care about results. If you’re not producing superior results relative to your peers, then you’re not superior to anything. This should go without saying.