Do you mean a cover or while the fabric is still on the chair?
While it’s still on the chair
I haven't, but here's a link that should help:
I've used RIT dye for covers.
Hello. I have seen paint projects. This hometalk link might be a solution to consider. Hope this helps
I like this tutorial for painting upholstery: https://www.11magnolialane.com/tutorial-how-to-paint-upholstery-fabric-and-completely-transform-a-chair/