Hi Terry,
You need to get set up with Adobe's ExtendScript plug-in for VS Code. Have you done that? If not, go here:
This might not get you autocomplete, though--I'm not sure if they've added it yet. I'm still using the ExtendScript Toolkit app (in Windows, it doesn't run on newer versions of the Mac OS because it's 32 bit, and because Apple). My feeling about the plug-in for VS was that it wasn't "ready for prime time"--but I haven't looked at it for a bit.
Thanks,
Ole