If the framework is correct in design and implementation then you can change something superficial and the odds are good that the change is superficial and it works.

If you are starting from the outside and working in it might seem easy to get started but you will fall behind in productivity compared to people who do the opposite.

I have frequently worked with testers and frequently those testers have chosen to automate their work and I am all for that; a dev doing the same might catch some errors that way but they may also encode conceptual mistakes.