I have one fixed, three different colour layers in a single project. I want to create an SVG font that includes three instances for each colour combination. If it is possible, I would like to solve this issue in a single file rather than exporting three different files.
You can set it up as a COLR/CPAL font. Add multiple palettes and a
Color Layers to SVG and
Color Palette for SVG in each instance.
I have this repository that should help. One file does SVG and CPAL export as well as multiple colour palettes (see Font Info > Masters > Color Palettes).