environmentImage property
Controls the environmental reflection of the model. Normally if skybox-image is set, that image will also be used for the environment-image. Use environment-image to only set the reflection without affecting the background. If neither is specified, default lighting will be applied. If 'neutral' is specified without a skybox, then a more evenly-lit environment is applied instead.
<model-viewer>
official document: https://modelviewer.dev/docs/#entrydocs-lightingandenv-attributes-environmentImage
Implementation
final String? environmentImage;