N T N studio

Think of your object floating within a sphere, the HDRI is mapped to this sphere. In order to "ground" the object more firmly, try hitting the "g" key.This flattens the bottom half the spherical environment up to the ground level. It distorts the environment, but can look okay in many cases. This "flatten ground" option can also be enabled in the Project>Environment tab under the "Advanced" setting at the bottom of the menu. The best possible way is to combine a backplate with the environment.

For me the best solution to get an appreciate goal, is: _ use the hdri environment, playing with it , untill you can find a reasonable and a realistic model position, that could match with the ground- _ then, hide the 3d model from the keyshot scene, and start the render; so you will get a render image of that position _ use that image as backplate and the hdri environment as lighting, so u can have light and backplate matching. _ turn on grid and 3d model on keyshot scene, and try again to match position. (if u have a car model, u can cut a bit the tyres so you will get realistic "weight". Many of my hdri environment are with big size 200-300 Mb , so for to manage with them, u must have a decent pc memory and power cpu... Regards