Kodi has no support for tonemapping and is unlikely to gain that capability anytime soon. Most hardware Kodi currently runs on either lacks the specialist image manipulation capabilities to do on-the-fly tonemapping, or the hardware can do it, but support hasn't been implemented in the Linux kernel and drivers yet; and hence there's no need (and not much point) trying to support it right now.
In simplistic terms: Kodi simply outputs video with an appropriate resolution, colour depth, colour-space, and HDR flagging as detected from the media being played and within the constraints of what the hardware (HTPC) can output. As not all hardware supports all combinations (read from the HDMI EDID data) Kodi will sometimes output in a higher bit-depth or nearest colour-space from possible output formats. It's then up to the display device (Monitor/TV/Beamer) to figure out how to display that combination.