With \markup { \score { can I separately control the score size?

[Richard Shann]

When \markup contains a musical quote as a \score block the size of the
music would generally need to be smaller than the main score.
I have got as far as putting #(layout-set-staff-size 12) in the layout
block of the \markup \score ...., but that's got obvious problems as
does using \new Staff \with { fontSize = #-2 } inside the \markup \score

Any clues how to do this?

Richard