I just joined a team in AWS and the team has approximately 8 L3s (SDE 1s) out of 12 people some of whom have been Amazon for approximately 3-4 years. I want to make sure I am set up for promotion and that this does not become an obstacle for me. How should I navigate this situation?
I'd start with writing more code (without sacrificing code quality) than every other SDE1. The first step to get promoted is being better than the average of your current level. The next step is to build the behaviors of the next level.
This course will likely help break down the path more thoroughly: https://www.jointaro.com/course/grow-from-junior-to-mid-level-engineer-l3-to-l4/
As a new junior engineer, you are almost entirely judged on your code as Jonathan mentioned before. There are 2 simple axes here:
On top of the L3 -> L4 course, I recommend the full learning path here: https://www.jointaro.com/learning-paths/nail-your-promotion-junior-to-mid-level-l3-to-l4/
Other ways to separate yourself as a junior (all of these are covered in the course/learning path):