Hi Deb, welcome to Permies!
I don't make many extracts, but I make a lot of tinctures and can confirm that you can absolutely make a tincture with turmeric root powder. The reason I choose tinctures is because they have the longest shelf life. They can keep for years and years in a cool dark place.
Here's a really good video by Mountain Rose Herbs on how to make tinctures. They're using cut and sifted herb in the video, but I make many of my tinctures from powdered herbs too.