Hi ncollins1985,
Yes but it depends exactly on what you you want to do.
You can get the computer to inbetween for you as long as it is using the same Grease Pencil (GP) points from both frames.
Just go to the empty frame between your two frames, make sure you are in edit mode then press the interpolate button or Ctrl Alt E
But if you have different GP points on both frames then that will not work. You will have to draw that frame.
So jump into Draw Mode and on the inbetween frame you can really quickly press, D and then B. But you have to be fast. This will insert a blank frame and if you have onion skinning on it will make it easy to inbetween.
(That is also located in Strokes>Animation>Insert Blank Frame)
Is that what you mean?