LibreOffice 7.6 has the new feature “Multicolor gradient”. I have added an item about that to the section Core/General in the ReleaseNotes/7.6 - The Document Foundation Wiki. This text contains links to the files InfoPresentation_MultiColor_Gradients_LO76.odp and MacrosForMCGR.odp.
It would be nice if these two files are reviewed. Please improve any errors you find or notify me.