ΔE 31.4, loose: different enough that you should pick on purpose. Witch Purple is a little lighter, cooler than RLM 23 Red.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 31). Witch Purple is a little lighter, cooler than RLM 23 Red.
The same difference applies the other way round: RLM 23 Red is a little darker, 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 RLM 23 Red on the colour wheel See Witch Purple on the colour wheel
All matches: RLM 23 Red equivalents · Witch Purple equivalents