Hi!
Thanks for reaching out to us with your question!
Unfortunately, there isn't any built-in option for dragging plot lines and it would require extending its' functionality with dragging possibilities. Perhaps you might be interested in a solution based on this topic:
viewtopic.php?f=12&t=50424. This approach requires adding a line annotation with control point disabled and dragging enabled only for x-axis.
Demo: https://jsfiddle.net/BlackLabel/jv7yut25/
Let me know if that was what you were looking for!
Best regards!