fieldOfView property

Used to configure the vertical field of view of the camera. Accepts values in both degrees and radians (e.g., "30deg" or "0.5rad"). Accepts any value between the configured min and max field of view. Any time this value changes from its initially configured value, the camera will interpolate from its current value to the new value. Defaults to "auto", which sets either the vertical or horizontal field of view to 45 degrees depending on the dimensions of the model and the aspect ratio of the canvas. Seamless poster transitions for arbitrary element aspect ratios are only possible using "auto".

<model-viewer> official document: https://modelviewer.dev/docs/#entrydocs-stagingandcameras-attributes-fieldOfView