I don't know much of anything about using the command line. But there's a reference on the website: https://inkscape.org/en/doc/inkscape-man.html
If that doesn't help, hopefully someone else can answer.
If there is some info missing from that reference, at least I could see to getting it added though.
Multiply effect and font replacing
Re: Multiply effect and font replacing
Basics - Help menu > Tutorials
Manual - Inkscape: Guide to a Vector Drawing Program
Inkscape Community - Inkscape FAQ - Gallery
Inkscape for Cutting Design
Manual - Inkscape: Guide to a Vector Drawing Program
Inkscape Community - Inkscape FAQ - Gallery
Inkscape for Cutting Design