Rendering of 3D model

The look and feel of the model in Cesium is changing based on part of the day(like morning and night).
Kindly let us know if this can be suppressed.

There may be different ways to achieve that, depending on the question of which lighting conditions you want for your model. Maybe you just want to set a fixed time in the Cesium viewer, as in

const time = Cesium.JulianDate.fromIso8601('2013-06-20T11:00:00+00');
viewer.clock.startTime = time;
viewer.clock.currentTime = time;