Do any programming language function calls internally call Operating system APIs?

To list directory content in Python we use os.listdir(), In Java we use Files.list(new File(dirName).toPath()). Like this we use a lot of functions calls, eg: For Network connectivity, Print in screen, Save to files.

In all operating systems do these all language-specific function calls ultimately call OS APIs (In Windows I think it will be Win32 APIs)?

ANything we can do without call OS APIs?