Avoid involuntary data pushing to iCloud during updates
This is a bug that affected the update to iOS 10.3. Apple has resolved this issue with iOS 10.3.1.

See also Apple Warns iCloud Users Some Disabled Services Were Accidentally Re-enabled in iOS 10.3

iCloud sync settings are not supposed to change after an iOS update. In the case of iOS 10.3 this was due to a bug.

To answer your question: You don't need to change any settings to prevent iOS to enable any iCloud sync settings with 10.3.1 and higher. Older iOS releases (10.2.1 and 10.3) can not be updated to any more.