When I want to edit the settings, is there always a .json file and a gui I can use?

There is a settings.json file where you can manually type in the property name as well as its value. This is preferred when you are importing settings files from some other place or sytem. Alternatively, you can click on the settings icon directly in the vs code (left bottom ) which will take you to a screen, where you already see all the setting properties. On changing any of the values here, the settings.json will be getting updated automatically for you. This has less chances of errors.