cameraTarget property
Set the starting and/or subsequent point the camera orbits around. Accepts values of the form "$X $Y $Z", like "0m 1.5m -0.5m". Also supports units in centimeters ("cm") or millimeters ("mm"). A special value "auto" can be used, which sets the target to the center of the model's bounding box in that dimension. Any time this value changes from its initially configured value, the camera will interpolate from its current position to the new value.
<model-viewer> official document: https://modelviewer.dev/docs/#entrydocs-stagingandcameras-attributes-cameraTarget
Implementation
final String? cameraTarget;