Lightroom mobile presets are images that come with pre-applied settings that have DNG format. You just need to copy settings from this DNG file and paste them to the photos you would like to edit in Lightroom mobile app.
Mobile Lightroom preset is created in Lightroom Desktop, and they are exported to DNG format for using them with Lightroom Mobile App.
Lightroom and Desktop Presets both work the same but, they have different formats. Mobile presets using DNG Format, and Desktop Presets have XMP Format.
Also, if you would like to edit in Lightroom Desktop, you need an Adobe Lightroom subscription. In another way, for Lightroom Mobile App, you don’t need a subscription; it’s a free app.