Is a Toyota Corolla a good first car?

I tinker with cars as a hobby, and I want to try and help a friend whose check engine light is on in her 2019 Honda Fit. However, I’m not familiar with Hondas and don’t want to waste too much time. Where is the OBD port on a 2019 Honda Fit?

How do you open the gas tank on a 2015 Toyota Sienna? The door doesn’t pop open when I press on it, but I also don’t see a button for it inside the car.

I’m thinking about getting a certified pre-owned Porsche 911, and I’m wondering if it’s worth getting Porsche’s CPO warranty. But I’m not sure if it’s worth it—what is covered by the Porsche CPO warranty?