ΔE 8.3, close: similar, with a visible difference side by side. Khaki is more muted, warmer than German Sand Beige RAL 8031.
Usually, if you are not matching paint already on the model. Close match (ΔE 8). Khaki is more muted, warmer than German Sand Beige RAL 8031.
The same difference applies the other way round: German Sand Beige RAL 8031 is more saturated, cooler.
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 German Sand Beige RAL 8031 on the colour wheel See Khaki on the colour wheel
All matches: German Sand Beige RAL 8031 equivalents · Khaki equivalents