ΔE 11.4, fair: the same colour family, but not a straight swap. Plague Brown is a little darker, more muted, cooler than Naples Yellow.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 11). Plague Brown is a little darker, more muted, cooler than Naples Yellow.
The same difference applies the other way round: Naples Yellow is a little lighter, more saturated, warmer.
ΔE is the colour difference between our two swatch estimates: under about 6 is close, over about 15 is loose. Real paints also differ in finish, coverage and how they thin, so test before you commit.
See Naples Yellow on the colour wheel See Plague Brown on the colour wheel
All matches: Naples Yellow equivalents · Plague Brown equivalents