Settings & keep-time · Advanced, self-backup and Demo Mode
What does "Fit cleanup to this Mac automatically" do?
Short answer: It lets Storage Studio find the caches your installed apps create and keep them tidy automatically, while only ever clearing safe, regenerable cache folders. It's under Cleanup rules in Settings → Advanced.
With it on, Storage Studio finds the caches your installed apps create, so new apps are kept tidy without anyone editing a list. Deletion always stays inside safe, regenerable cache folders — never your settings or documents.
It's under Cleanup rules in Settings → Advanced, with Review Auto Rules… to see what it found and Re-scan now to look again.