I just have experienced a very similar problem (the settingsSettings app immediately crashes on opening, de-facto making any kind of access to phone settings impossible). Since this is the first hit for such a question on googleGoogle, I'll describe my case and the fix here:
The problem in my case was that the Settings App
Settings app somehow depends on the Google App
Google app and crashes when the Google Appapp is up to date-to-date (at the time of writing this). It is certainly the case that my phone's androidAndroid version is rather ancient (9) and could be due to some oversight on the manufacturersmanufacturer's side, but this nevertheless is a fairly recent regression and googleGoogle will hopefully fix it in the future.
As a temporary fix, resetting the Google Appapp to factory via "uninstall" + prohibiting auto-updates for the Google Appapp works.