Of the Shatner movies, I only have 2, 3 and 4 on DVD. I bought them in a set called “Star Trek: The Motion Picture Trilogy”.
https://www.amazon.com/Star-Trek-Picture-Trilogy-Domestic/dp/B001TH16CY
I don’t know anything about where they were sourced.
That came out same time as the blu-ray debut in '09. Khan’s transfer is likely from the '09 restoration. The Search for More Money and The One With The Whales were probably from the new (ha!) “hd” (ha!) masters, but I have no way of knowing for sure without seeing screenshots.
Here is a comparison between the old two-disc releases of Khan and SFS and their blu-ray counterparts ('09 blu-ray for Khan). Annoyingly, they did not provide dvd screengrabs for Voyage Home. I’d very much like to know what it looked like after seeing it in 35mm. The blu-ray’s colors are way off from what I saw on that print.
ETA: SwissArmyTin beat me to it!