Changing shutter speed alone does not increase the sensor’s inherent dynamic range if overall exposure is kept equivalent. If a scene’s brightness range exceeds what the sensor can record, some highlights or shadows will still clip regardless of using, for example, 1/60 at f/16 versus 1/125 at f/8.

The setting that most strongly affects captured dynamic range is ISO: higher ISO generally reduces dynamic range, so use your camera’s base/native ISO when possible for maximum latitude. Very long exposures can add a little extra noise from sensor heating, but that effect is usually much smaller than the dynamic-range loss from raising ISO.

An ND filter only reduces all light equally; by itself it does not compress the scene’s contrast or give the sensor more dynamic range. It’s useful if you want a longer shutter speed for creative reasons, but not as a direct solution to a high-contrast scene.

For scenes like sunsets, the practical approach is to shoot at low ISO and, if the scene still exceeds the sensor’s range, use techniques such as exposure blending/HDR, graduated ND filters, or other methods that effectively apply different exposures to bright and dark areas.