This looks like an Andy Warhol-style famous-for-fifteen-minutes portrait of John Carr but the idea is to come up with a colour harmony that will suit the Carr Tricentenary exhibit in the Redbox Gallery in Horbury.
Procreate includes a Colour Harmony Wheel so starting off with the colour of Yorkshire stone – the coal measures sandstone of St Peter’s Church – I’ve experimented with the various options available. Complementary does give me enough colours, Tetradic gives too many fighting against each other, so it’s the Split Complementary, Analogous and Triadic that are most likely to give me a workable colour scheme.