You can use the Files app to view files from iCloud, Google Drive, Dropbox, and so many more.
The Files app, introduced in iOS 11, is the central repository for all of the files services with apps on your iPhone and iPad, like iCloud, Google Drive, Dropbox, and many more. It lets you open documents, photos, videos, and audio from any compatible app from a single point on your device.
How to get the Files app on your iPhone or iPad
The Files app replaced the iCloud Drive app in iOS 11, but unlike the iCloud Drive app, Files has no special switch to hide or reveal it, and it appears on your iPhone or iPad running iOS 11 or later by default. If you want to get rid of it, you can just delete the app, and restore it later by downloading it from the App Store.