SVG doesn’t support DPI for vectors, the scaling is set by the ratio of coordinates/object sizes to the overall size of the document (actually the viewbox in the XML but that’s not a term used in Inkscape). Hence no DPI setting.
The default coordinate system and sizing parameters are mm. If you open a SVG file with a 20x12 inch workspace, you’ll find the viewbox is defined in mm to match.
I made a mini (8.5") cuz that’s the spare material I had, and defocused the score (I set the material height for that one command to .5") and it’s adorable! I think I’m going to paint it bright colours and hide it in my friend’s garden