Accessibility - Updating Page Templates to include Landmarks

I am in the process of updating a site to better support WCAG standards.
One of the items I would like to add is “landmarks”
https://dequeuniversity.com/rules/axe/4.8/region?application=AxeChrome

Essentially this requires adding roles to different sections of the page templates.
e.g.,

This is the header
This is the nav
This is the main
This is the footer

I know I can edit the theme layout files directly, but I suspect there is a way to overlay these div tags to existing elements on the page, but I’m not sure how to go about this.

Ideas?