You can use LibreOffice extensions to add colors palettes, gradients lists, or hatching patterns lists.
If you have a custom palette available as an extension, use the Extension Manager to load the palette in LibreOffice:
Open the Extension Manager.
Select the extension file (usually a file with oxt file extension)
Click. You will be asked to restart LibreOffice.
Loading color palettes from the Area dialog box brings a dialog with all color palettes available in the LibreOffice Extension Website.
Choose Format - Area, and then click the Colors tab.
Click the Add color palette via extensions button. A dialog with all available color palettes in the LibreOffice extension site will appear.
Locate the color list that you want to load, and then click Install.
Close the Extension dialog.You will be asked to restart LibreOffice.
The freieFarbe HLC color list is based on the CIELAB model and is optimized for professional CMYK printing.
The colors in the Compatibility and HTML palettes are optimized for displays using a resolution of 256 colors.
The palettes “LibreOffice” and “Material” contain the official LibreOffice and Material Design palettes respectively.
The "tonal" palette provides a set of colors organized by luminance contrast that work across different hardware.