You access that folder via the Finder sidebar > iCloud Drive or via the Finder "Go" menu > iCloud Drive.
You can also hold down the option key in Finder in Sonoma and while holding the option key, click the Finder Go menu then click Library and then click the iCloud Drive folder (used to be named mobile docs). All roads lead to the same place -- your local copies of iCloud Drive files, including Desktops and Documents files if you have that option turned on.
If you don't have the Optimize Storage option turned in Apple menu > System Settings > [username] > iCloud > Optimize Mac Storage then all of your iCloud Drive files will have a local copy at that location.
If you do have Optimize Mac Storage option some files may still have a local copy depending on the storage available on the Mac. See the "View iCloud Status" section of Get file, folder, and disk information on Mac - Apple Support for instructions on how to determine the status of the files.