On my iPhone 8+ Scrivener updated automatically to 1.1.4 (1274) and uses the new icon.
On my iPad Pro it didn’t. It shows up with the old icon, and doesn’t feature among recent or pending updates from App Store. If I go to the App Store and search for Scrivener, it comes up – with the new icon – as an app I can “Open” (as distinct from i.e. “Download”, “Update” or “Buy”). If I click on “Open” within App Store, Scrivener opens on my iPad, but still with the old icon and in the settings the version is still 1.1.1 (964).
Again, according to the settings, neither my iPhone or my iPad need to upgrade its operating system. (For the phone the current operating system is iOS 11.1.2, and for the tablet it is iOS 11.2).