My sky q main box picture resolution is 2160p, is the right for Sky q box and for HD
If your Sky Q main box is displaying at a resolution of 2160p (which is also known as 4K or Ultra HD), then yes, it's capable of delivering high-resolution content. Sky Q supports 4K content for certain channels and on-demand services, provided you have a compatible TV and a subscription that includes 4K content.
For standard HD content, the resolution is typically 1080p (Full HD). If you're watching HD content, it usually will not come in at 2160p unless it's specifically a 4K version of a show or movie.
In summary, having your Sky Q box set to 2160p is correct and allows you to take full advantage of 4K content, while HD content will be upscaled to that resolution if your box is configured that way. Make sure your TV settings also support and are configured for the best viewing experience!