Currently, HDR is not supported on Caavo.
HDR stands for High Dynamic Range and is specific to the color space and color enhancement capability of your TV/display. HDR basically provides a wider color space than the current standard color space in older displays/TVs. HDR is not related to TV/Display resolution and should not be confused with resolution identifiers. Ie. HDR is not HD, HDR is not UHD, and HDR is not 4K.
You may watch content that is produced with an HDR color space, however the color information for that content will be shown within the standard color space.