On the Mac, the System Preferences app only really contains settings for the system itself, and the settings for each app will be found in that individual app for the most part.
The name "System preferences" on the other end is indicative of the fact that this is not where you find the app settings in and that you have to look for them in the app itself.
So, how do third-party preference panes in System Preferences fit in then? Any Mac app can put its own preference pane into System Preferences to store settings if it wants, just like iOS. Admittedly, I don't think this is extremely common anymore (if it ever was).