This is an accepted solution.
Ren here from the Shopify Social Support team - thanks for your question.
It does look like we have an app integration that may do just that called Duplicate.
The app page has a full list of what it can and can't copy and a detailed overview of their pricing structure. Product exports are free - everything else comes with a cost.
Another option would be to export your data via CSV: (directions here) and to re-purchase the theme you'd like a copy of since a purchase of that theme is required for each store account for a valid license to use the theme.
What changes are you hoping to perform by copying a live store into development? I'd love to see if I can help!
Thank you for the recommendations. I think we will go with using the Duplicate App. We were planning to make some of our changes in development store before going into the live site. No concrete plan yet, but just planning ahead.
Thanks for your question! I checked into this and at this time the steps I outlined above are still the best method for copying a live store to a development store. That being said, I can certainly pass this along to our feedback team for consideration and I appreciate you bringing your concerns to my attention.
If there's anything further I can do to help please don't hesitate to let me know.