Any guides on creating 10 bit HDR textures for Unreal?

Says HDR in Unreal can now take advantage of a wider color gamut. rec2020. You’re telling me rec 709 and rec 2020 are the same exact thing and it’s simply based off how the engine handles light? So in short, i can take a rec 709 texture and that will be appear just as an HDR texture does when I enable this setting?