Iphone 7 Storage Issues

I have purchased iCloud and I still have issues with memory storage in my Iphone 7 32GB, is there any other way that I can access the "Other" or "System" folder so I can erase/delete unneeded info i.e. downloads, cached, etc. to clear up more space? They currently are taking more that half of the storage, ~ 21GB, in my device. Any help will be appreciated. Thanks!