How can I change color of pampas grass
Certified GKH Gardening Expert
You won't be able to. There are very few shades of pampas grass, and they are colored by genetics. Changing this would require many generations of breeding.
There are many colorful grasses that are often mistaken for pampas grass that may interest you, though. This collection of articles will help: https://www.gardeningknowhow.com/ornamental/foliage/ornamental-grass