ΔE 15.9, loose: different enough that you should pick on purpose. Plague Brown is a little darker, much more muted than Intense Yellow.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 16). Plague Brown is a little darker, much more muted than Intense Yellow.
The same difference applies the other way round: Intense Yellow is a little lighter, much more saturated.
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 Intense Yellow on the colour wheel See Plague Brown on the colour wheel
All matches: Intense Yellow equivalents · Plague Brown equivalents