GIMP by itself cannot open RAW files but if you integrate it with a free third-party plugin like Darktable, then it can. In this video we will be seeing how to open RAW images using GIMP and Darktable.
Link to install Darktable:
https://www.darktable.org/install/
Link to the full online course on GIMP:
https://www.creativepadmedia.com/udemy-gimp-photo-editing-course