Several ways to bring out colors in a grow
Temp drops. I got purple from 10 days of 60 degrees off cycle in a tent.
You can also get purple from micronutrient deficiencies but I am not sure what nute is what color.
There are some fellas learning how to steer these deficiencies by upping or lowering pH to swing a reduction in uptake but at the same time ups the other nutrients that will loose effectiveness with the pH switch.
Nothing consistent yet but there is a marked increase in some strains.
And of course there are strains that can do this such as my next run. Reports are 10% of the plants will pink up and if I get one imo learn how to clone.