You explicitly select what scopes you ask for and then can attempt various API operations to see if they can be performed with the requested scopes.
Fragments can be added to explore different API's and aspects. This is much like the Google API explorer, but the testing is done inside a hopefully well structured Android app that allows functions to be tested as they are incorporated into other Apps.
The ultimate security and privacy of your data is determined by Google policies regarding Google Calendar, Google Drive, and Google Sheets documents.