+1 to Chung's reply. There's also a loader API where you'll generally never need to see the code that is output. Check out the differences between loader API and codegen here: https://docs.plasmic.app/learn/loader-vs-codegen/
In case you still want to see the code from codegen, here's an example. We generate 3 files per page/component:
While 1 and 2 will be overwritten as you update your project in Plasmic (and therefore you should never modify it), the wrapper (3) is yours to customize as needed, like setting props or binding event handlers. In the above example, we computed how much free trial time a customer has. You can read more about the generated code here: https://docs.plasmic.app/learn/codegen-components/