If I change the video quality from normal, to best is it similar to hd in the discovery plus app on sky q

Yes, changing the video quality to "best" in the Discovery Plus app on Sky Q generally provides a higher resolution similar to HD (high definition). The "best" setting usually ensures that you are streaming in the highest available quality, which would typically be 1080p HD or higher, depending on the content and your internet connection. If HD content is available, selecting this setting should allow you to experience the best visual quality the app offers.