This command has moved
Copy External Bookmarks has been merged into Copy Bookmarks, together with the former Copy Bookmarks from File.
The two commands always shared the same underlying engine and differed only in which options each one put in front of you. The merged command offers everything both had: a single PDF or a whole folder as the source, the current document or another PDF on disk as the target, and a choice of whether the copied bookmarks point back at the source or at the target’s own pages.
Everything you could do here you can still do — see Copy Bookmarks. In particular, the Preserve actions and Remap actions choice is now Where the copied bookmarks point.