what do you mean by “properly mapped” ?
Converted, really. This is known as HDR to SDR “tone mapping.” The long and short of it is that when you try playing HDR content on a monitor or device that can’t correctly display the REC.2020 color space (which is the color space that just about every 4K disc uses for the feature film), it spits out a gray, washed-out image. So you either do the obvious and upgrade your devices to those with HDR display capabilities or convert the HDR content in question to 8-bit standard dynamic range (SDR) video with a REC.709 color space, allowing you to watch it on just about any device with no significant display or color issues.
That latter scenario would be the solution if you want to watch, say, the newly-remastered Prince of Egypt in 4K, but on an SDR monitor because the standard 1080p Blu-ray does not carry an SDR version of the new transfer. (Which it does not.)
1998/2018 1080p Transfer
2023 4K Transfer [Tone mapped from HDR Blu-ray]
