Noise at ISO 100 is usually not caused by the lens, and not by ISO alone. In sunrise scenes the real issue is the huge brightness range: the sun is extremely bright while the foreground is much darker. If the darker areas are underexposed and then brightened later, they can look noisy even at base ISO.

So the likely cause is exposure and scene contrast, not a faulty lens. To reduce noise, gather more light where possible (longer shutter speed, wider aperture, tripod if needed) and avoid lifting very dark shadows too much in post.

For white balance, don’t use a setting that neutralizes the warm color if you want a reddish sunrise. Daylight or Cloudy usually preserves or enhances the warm tones better than Auto White Balance.

For metering, spot metering directly on the sun usually isn’t very helpful because the sun is much brighter than the rest of the scene. A better approach is to meter the overall scene and use exposure compensation, or expose for the sky near the sun depending on whether you want silhouette foregrounds or more shadow detail. Sunrise often exceeds the camera’s dynamic range, so some clipping or dark shadows are normal.