The Assist AR app for Android requires ARCore in order to make use of augmented reality.
💡Hint: For iOS devices, the technology providing AR is called ARKit.
This article applies to all TeamViewer Assist AR users using an Android device.
Here you can find the list of Android and iOS devices that support ARCore / ARKit:
ARCore supported devices | Google Developers
💡Hint: Once your device gets an update and is able to use ARCore, you automatically get the full AR experience with 3D annotations.