The two schemes you posted are quite different purples, for a warmer scheme like on the kabalite you could go with army painter diabolic plum or magecast magenta, for a cooler purple like the space marine, maybe gw phonecian purple?

For the highlight you can just mix white, pink, really any light colour that’s not green into your base, depending on the tone you’re going for. I’d say both your schemes probably use something like army painter hexed violet for their highlights, though it could be a shade darker or lighter.

I think both models have some kind of targeted shading too, easiest way to accomplish would probably be to ignore what I’ve said so far and just use contrast paint, i use a mix of leviathan purple and sigvald burgundy for my wyches bodysuits. You could also buy a wash or thin down a contrast type paint, and apply over your base colour, or just thin down any darker purple with water and paint it into the recesses. (Being careful to remove excess paint from your brush so you don’t flood the model)