Are you talking about upto the scrolls record export or what?
Export as Image. It will give you image of whole dashboard. Then you can covert that image into PDF.
You can see that in below image, We are not able to see all dashboard. We need to scroll it.
Here I have exported as image and given image of whole dashboard.
Please compare if you have doubt. try this and let me know if you face any issue.
Please mark correct and helpful if it works for you.