Thankfully, there are still ways to see the original films. Lots of "despecialized editions" and the like are out there. One of the most interesting are the 4K77/80/83 restorations which bring back the original film grain. It's a little less watchable as a movie, but very interesting to see how different scenes used different film stock for different reasons, without modern color correction, etc.

97% of project 4K77 is from a single, original 1977 35mm Technicolor release print so if it goes from blurry to sharp, grainy to not grainy, bright to dark, that’s because it also did that in 1977. Color correction was a single correction per reel – the optical audio track was used to white balance the image, and the contrast adjusted to ensure that there was no clipping of the highlights or crushing of the blacks, so if the color changes from shot to shot, or it goes from very dark inside to very bright outside, that’s how it is on the print. Film has a greater contrast range than home video, and of course was graded for viewing, reflected off of a giant silver screen.

Star Wars was shot on four different types of film stock, some grainier than others. (Kodak 5243, an intermediate, probably for composites, 5247, a fine grain 100 EI tungsten stock that the live action must have been shot on, and 5253, an intermediate used as a separation stock that all visual effects elements were shot on, plus the CRI stock [Magid, Ron. “Saving the Star Wars Sequels,” American Cinematographer, February 1997.])

The Effects, the music, the editing all continued right up to the last possible moment. Some scenes were shot out in the deserts of tunisia, where the sand got into everything including the film stock. Some scenes were also filmed with nylons over the lens, others were not. Scenes filmed outside, particularly in the desert, that are supposed to be only moments apart in the narrative, may actually have been filmed hours or even days apart, with the sun and clouds in constant motion and the lighting conditions changing greatly. Color correction and film printing back then was a photo-chemical process, so not all of these shots match as perfectly as they might if shot today and corrected using Davinci Resolve, watching the scopes and turning the color wheels. This also meant that no two prints would be 100% identical, and that the alignment of the Cyan, Yellow and Magenta layers of the Technicolor prints was not always perfect – which is why you can often see green or red fringing on objects in project 4K77.

Many of the visual effects shots were created using a technique called “optical printing”. Each element of the shot (starfield, X-wing, Y-wing, Tie fighter, laser blast) would be shot separately, with the ships against a blue screen. They would be combined by projecting all the images at once onto a new piece of film, a process that often allowed additional dirt, dust and hairs to be baked into the film, softened the image, and added additional layers of grain.

All of these factors mean that scenes filmed on set at Elstree, where Vader and Tarkin are just chatting in a room, are a heck of a lot cleaner, sharper and less grainy than those of R2D2 and C3P0 wandering about in the desert. It’s easy to forget that this is how it was for twenty years – all of these flaws can still be seen on the Betamax, VHS, CED and laserdisc releases of the 1980s.

https://www.thestarwarstrilogy.com/project-4k77/

Not downloadable directly, but if you don't mind sailing the high seas or can figure out the Internet Archive's archaic search, you can find them.