The ViewCube supports “animated transitions”, which are the smooth changes between different viewing angles.
There’s a hidden (aka officially unsupported) preference that extends animated transitions to everything, like the F and A shortcut keys for framing objects.
SetValue "Preferences.camera.animate", 1
There’s also another [hidden unsupported] preference to change the camera transition speed for this hidden feature:
SetValue "Preferences.camera.animateduration", 0.25
Value is in seconds. Default is 0.5, and be careful not to set it too high by accident…
Note On Linux, there’s a viewport glitch with this preference, so I wouldn’t use it.