Yes. Long exposure noise reduction generally affects RAW captures as well as JPEGs.

This feature works by taking a second exposure with the shutter closed (a dark frame) and subtracting that sensor noise/pattern noise from the original image. Because it uses data from a separate exposure, the correction is applied before or as the RAW file is written, so you typically still get just one RAW file and not the dark frame itself.

That’s different from standard high-ISO or JPEG-style noise reduction, which is often only applied to processed image data and can be redone later in software.

The main downside is speed: with long exposure NR enabled, each long shot can take roughly twice as long because the camera must make the matching dark-frame exposure. For night or astrophotography, some photographers prefer to leave it off and create/apply their own dark frames later to avoid losing shooting time.