I actually think I've figured this out but would love to hear yalls thoughts here too.
At first I was against the idea of writing a character smarter than myself since it was a rather intimidating idea. I had seen and read terrible smart characters which felt omnipotent and made nearly no sense to me. On the other hand I read characters who were just genuinely well written and smart and I couldn't realise why.
Recently I came to the conclusion that the answer is simpler than I thought. Not just that it's a rather universal feeling. The feeling of being unable to express an idea you know well but can't seem to explain out loud. All you need for a smart character is perfect recall. To remember everything all the time.
Not knowing, not deducing, remembering and communicating.