A lot of the features of accessible PDFs are only editable through readers such as Adobe Acrobat and cannot be adjusted before the fact.
But I make all my PDFs in Word first!
That is fine, in the Microsoft Word (or Google Doc, etc.) file, you can control things like the content structure; i.e. headings, paragraphs, lists, reading order, basic tables, inline images, columns.
However, accessible tags for references and notes can only be fixed in the exported PDF document, as there is currently no way to remediate a Word Doc to preserve the accessibility features when exported to a PDF.
Tags for references and notes are created when the file is exported by the Acrobat distiller from .doc into PDF format.
So what should I do if I want to keep writing in Word?
Have a read of this great resource on Microsoft Word to PDF accessibility to help guide you as you are writing: Creating Accessible PDFs in Microsoft Word.
And then reach out to your Customer Success Manager at Level Access to ensure Remediation of PDFs is a service included in your contract!