For best results, it's done in salon by professional stylists.
However there are products on the market that claim to do the same thing hair Botox treatments do.
I don't have experience with either of these, but if I had to choose I'd pick the in salon treatment, because a professional is doing it and they'd have the legit products lol. But cost wise it's pretty expensive especially for long hair, I guess it won't hurt to try one of the hair Botox masks/treatments.