I love colour discussions. Nothing quite like them for generating heat on a cold day.
There are those with colour chips they’ll claim are definitive, but that (while useful) is not the whole story. Paint colour generally changes over time, and colour perception is not simple. There are also interesting arguments for ‘scale’ colour as perception changes with distance (tending blue, and lower saturation). If you are viewing a model from 1-2m distance, this might be 100m scale where such effects start to be relevant. Colour is also dependent on the light used to view the result. No point in getting something that looks great in daylight if your layout is lit with incandescent.
Then there’s the effects of weathering.
So these days I don’t get too hung up on the ex-works, as new, colour unless I want to simulate that condition. You can estimate a useful model colour match with the method here: https://nzfinescale.com/what-colour/. It’s not perfect but has it’s uses. There are apps that do similar things too. I find it’s not bad to produce a starting point and I can always mix a bit of something else to adjust if I feel the need.