Configuring content elements can be done for the frontend and the backend.
The easiest way to change the appearance of content elements in the frontend is by using the Constant Editor`*. These settings are global, which means they are not configurable in a single content element. Constants are predefined.
TYPO3 uses TypoScript as a configuration language and is used by the frontend rendering. By overriding TypoScript you can modify the rendering for most of the frontend.
For the backend, fields can be shown or hidden, depending on the fields you are using or the fields an editor is allowed to use. Configuration like this is done using Page TSconfig or User TSconfig.