I think the expectation is that sites will use the pre-seeded Contribute > Site feedback category for this. Its description is: “Discussion about this site, its organization, how it works, and how we can improve it.”
That’s an interesting idea. What benefit would it have over just having users suggest changes in regular topics? Is the goal to have a way of keeping track of changes that have been made to the site’s configuration over time?
Site settings, categories, tags, policies etc, can be configured with the Discourse API. It might be possible to have a script that managed your site’s configuration via the API in a git repo. The script could be run when a PR on the repo is accepted. From my point of view this would be more difficult than manually making changes to the site’s config via the UI though.