I’m not completely certain, but I think the basic workings of autoinit are the same for VTK 9. But the dependencies might have been shuffled around a bit.
Before #include <vtkAutoInit.h>, you will need definitions like this:
#define vtkRenderingCore_AUTOINIT 1(vtkRenderingOpenGL2)
The documents for autoinit are here, they’re cmake-centric but they describe some of the inner workings.
Edit: it might be more like this:
#define vtkRenderingContext2D_AUTOINIT 1(vtkRenderingContextOpenGL2)
#define vtkRenderingCore_AUTOINIT 3(vtkInteractionStyle,vtkRenderingFreeType,vtkRenderingOpenGL2)
#define vtkRenderingVolume_AUTOINIT 1(vtkRenderingVolumeOpenGL2)