VFB Composition Guides and Panorama Viewer
In V-Ray 6 we have different composition rules built into the VFB. Going to the layers we can find the proportion guide. This is very handy because we can continue rotating our camera until we find the right spot.
Something else very useful is the panorama viewer. To enable it we have to go to the renderable camera and add a camera settings attribute. Then we have to make sure we are rendering with a spherical camera type.