If you want the Star Wars original unaltered trilogy versions of the films in digital format (DVD), then you’ll need to buy the Limited Edition DVDs as each package contains the original unaltered version in addition to the modified special editions. Original unaltered trilogy refers to the original theatrical versions of the first three Star Wars films, A New Hope, The Empire Strikes Back and Return of the Jedi, before they were modified for subsequent re-releases.
Currently on Disney Plus, all Star Wars original trilogy versions are the modified versions. The only way to watch the unaltered versions is to get the limited edition DVD versions of the movies. Because Star Wars movies have been re-released so many times with different packaging, look for the case that says Limited Edition in gold background for the widescreen version and in blue background for the full screen version.