Welcome to the forum!
This is the only one I know about:
https://inkscape.org/en/~frmdstryr/%E2%98%85inkcut?c=1871 More info:
https://github.com/codelv/inkcutBut there are a couple of other extensions which export HPGL. This is a fork of InkCut:
https://github.com/slandis/InkCutter. And there's this one, which works with Modela brand engravers:
https://github.com/matthewbeckler/modela_inkscape_extensionOr else if you don't specifically need HPGL, there are lots of other extensions for cutting. It depends on specifically what you need. See the Home tab on this website, and on the bottom part of that page, you can see a listing of most of the external extensions (click on each list item to expand it). There are also a few built into Inkscape, such as Extensions menu > Export, or Gcodetools (if you need gcode).
Also on the bottom part of that page are the general instructions for installing extensions (somewhat simplified, for newbies). However, if the extension you choose has it's own instructions, you should follow those instead.