Not in the usual sense. A RAW file isn’t a finished color image; it mostly contains sensor sample data arranged in a Bayer pattern. Because of that, you generally can’t just “resize” a RAW file the way you would a normal image.

To reduce it to about 5 MP, you normally need to process the RAW into an image format first, then resize that result. That output does not have to be JPEG—you could use TIFF or PNG if you want to avoid JPEG compression.

If you want to stay closer to the sensor data, tools such as dcraw can extract the RAW data to a TIFF, but resizing that correctly is more specialized because of the Bayer pattern.

Without demosaicing, RAW downsampling is only practical by whole-number factors in each dimension, so a 12 MP file would typically drop to about 3 MP, not 5 MP. So if your target is specifically around 5 MP, the practical route is: develop the RAW, resize the image, and save to TIFF/PNG/JPEG as needed.