A new mod that enables HDR in non-HDR enabled games on RTX graphics cards has been released over on NexusMods, and users are reporting it's better than the AutoHDR setting native to Windows.
The mod is called NVTrueHDR (via Videocardz and the Guru3D forum), and it comes from user emoose. It's not entirely built from scratch, however, the mod is built upon some hidden settings stored within Nvidia's GeForce drivers since the release of RTX Video HDR with version 551.23.
RTX Video HDR, first displayed back at CES in January, employs the help of a deep learning algorithm to convert SDR video into HDR video—dramatically improving the range of colours able to be shown on a compatible display. Turning on a few hidden "trueHDR" profile settings, however, and it appears this feature can be applied to games, too.
Reports from users suggest it's a pretty good application of HDR in some games, and an improved on the native AutoHDR feature baked into Windows 11. AutoHDR has to be disabled for this mod to work, anyways, but the mod has reportedly been shown to function from DX9 games up to recent DX12 titles.
Though the mod appears to have received plenty of positive reviews, there have been a few reported flags for the mod by Chrome's virus flagging software due to the executable file it includes. The mod's creator says they're trying to prevent any further flags, but obviously downloading files from strangers on the internet comes with its own set of risks.
Nevertheless, it would at least appear that Nvidia has played around with its own version of the software, as it's already including all the necessary components within its drivers. Whether that will amount to any sort of official release is another thing entirely, though it does seem like it could be another feather in the RTX cap. For gamers on non-RTX hardware, there's always AutoHDR, and Special K also offers HDR retrofitting for DX11 and DX12 games, though I've not tried that one out myself.