Some people reported being unable to search in Settings after upgrading to iOS 12. But a Redditor found a fix for it.
Search in Settings
u/kstrike155 came up with a clever solution to the issue.
- If you can’t search in Settings, switch the device language from English to English (UK).
- Close the Setting app, then go back in and switch it back to English. After that you should be able to search again.