Is there not some kind of app that will do this sort of thing for you?
Any access I make to adult content on my iPhone I do using the Chrome browser in Incognito mode - I don't use Safari for anything like that.
I never access adult content on Safari, even though it now has a private mode, I have three other browsers including Chrome which are better for private mode. But you can't delete Safari or switch off the feature that allows it to search all your social media apps for shared links - so all web links on my 'private' Twitter account show up if I forget to delete the account completely.
Never ever experienced such an issue in IOS that maps can monitor e-mail content but any address with post code it can find from searching content even not tracked by maps.
Think that's using Searchlight mode - but I switched that off for email, notes and texts years back when I found it discovering embarrassing emails, even ones that had been deleted and didn't exist! When you clicked on them it couldn't find them but it somehow still stored the text and showed enough to be incriminating.
I'd recommend turning off Spotlight Search, it's in - Settings/General/Spotlight Search - tap on the little blue tick next to each app name like email to stop it searching those areas.
But somehow Maps finds every postcode even without Spotlight - Apple must have coded it in, great feature but like someone on hear said, smartphones are becoming too bloody smart!