Here is why there are three preset file types for Lightroom... over the years, preset file types have been changed by Adobe depending on the Lightroom version being used. The three preset file types are:
DNG presets - Used with the free version of the Lightroom Mobile app that is not connected to a paid subscription with the Adobe Creative Cloud. DNG presets are not normally used on desktop versions of Lightroom. DNG presets take more time to install because each preset is saved inside a DNG photo file and must be saved, one at a time, on a mobile device.
XMP presets - These are the newest preset file format and they are the easiest and fastest to install. They are used with paid subscriptions to the Adobe Creative Cloud and are compatible with desktop versions of Lightroom CC, Lightroom Classic CC, and Photoshop CC. They are also compatible with the Lightroom mobile app. XMP presets cannot be installed directly into a mobile device, but first must be installed into the desktop version of Lightroom CC. Once they are installed there, they will automatically sync with Lightroom CC on mobile devices connected to the same Adobe Creative Cloud account.
LRtemplate presets - Used for older desktop versions of Lightroom including Lightroom 5 & 6, and Lightroom CC versions that have not been updated with the Adobe Creative Cloud (versions prior to 1.4) If LRtemplate presets are installed into a new version of Lightroom CC, they will be automatically converted to XMP preset files.