No - that's not the right answer.
My assignsubmission_pdf plugin was superseded by the version built-in to Moodle itself back in Moodle 2.6. It also only supports annotation of PDFs.
As of Moodle 3.1, there is support for auto-converting Word documents, etc. to PDF, before annotating them within the browser. See https://docs.moodle.org/en/Installing_unoconv for more details.
There isn't a plugin (that I am aware of) for directly annotating word documents inside Moodle (without converting them into PDF), but there may be plugins that interface to external systems for doing so.