How to handle peer pressure at Big Tech due to smart coworkers?

As a big tech worker (or least working in a company that mainly hires from big tech), I don't think I'm particularly smart. I got B's and C's in high school, went to a fairly bottom tier college, spent most of my life until junior year of college playing Maplestory, and took ~5 months to find my first job.

Reading over your question, it seems to me that you feel like there's a gap of technical and domain knowledge between you and your coworkers. If I'm indeed interpreting the question right, then I'd just put yourself in scenarios where you're interacting with coworkers more. More iteractions means that there's more oppotunties for their knowledge (domain and technical) & frameworks of thinking to stick to your mind. I'd recommend a few things.

• Review more artifacts such as code reviews or design reviews. In these reviews, ask questions on why things were designed in that particular way or if another specific design as alternatively consideted.
• Ask more questions in meetings. Similar to reviewing artifacts, look to ask questions when something is unclear to you (why did we decide this, have we tried doing x, how do we imagine y to scale when z conditions happen, etc.). You obviously don't want to ask too many questions to avoid slowing down the meeting, but if you ask a small amount of short, focused questions every meeting people will generally be comfortable answering those questions.
• Find a mentor. In big tech companies, there's generally a lot of experienced engineers who are willing to help mentor and grow others. See if your manager can pair you up with a more senior engineer who can help provide the information and support you need to be more productive.

Hope this helps!