For situations where you want to allow users to just enable or disable some options, you can consider the switcher field which allows only two values - true or false:
{ "name": "lazyLoad", "label": "Lazyload", "group": "Additional", "note": "Enables lazyloading images that are currently not viewed, thus saving bandwidth.", "value": true, "type": "checkbox" }
The switcher fields are great to handle conditional display of other options with use of the dependencies parameter described under Theme Settings API.