Get quick wins across the first month or so and then shift into the meatier, larger projects
Quick wins will let you acclimate yourself to the overall lifecycle of making production changes, which is an important engineering foundation to have
Another aspect to consider is team respect. Respect is gotten by generating outcomes, which quick wins obviously let you do, well, quickly.
You can use these smaller tasks to show your stuff. Back when I was at Instagram, a senior Android engineer joined my team and immediately won the respect of all the other Android engineers by going super deep on a tricky Android bug that was stumping everyone. This was just a 1-2 day task, which they were able to use to show a very impressive amount of depth.
For more great resources around effective onboarding, I recommend these: