An iOS app cannot uninstall another app, nor can it access the data of other apps, let alone delete it.
There no "good alternative" - or any alternative - because it simply isn't possible to do what CCleaner does on iOS.
(There are edge cases, such as suites of apps from the same publisher that are able to access each other's data.)
With permission, an app can access photos, and some other files in common. but I don't think that photo deduping, etc. is one of the functions of CCleaner. (I have it on my Mac, but can't remember when I last used it.) It's main purpose in life is to remove the detritus left over by uninstalled apps, and as a convenient uninstaller without having to figure out how a particular MacOS app is normally uninstalled.
CCleaner on iOS would make little sense.