In a twig, how do I access different fields of a specific content type in a taxonomy term page
When you display a taxonomy term the output is produced by this View:

admin/structure/views/view/taxonomy_term

The taxonomy term itself is in the header

HEADER
Global: Rendered entity - Taxonomy term (Global: Rendered entity - Taxonomy term)


and uses the taxonomy term template shown in your question, where you have only access to the fields of the term, not the content.

The format of the content is configured in the main part of the View. Default is to display the content as Teaser:

FORMAT
Format:Unformatted list | Settings
Show:Content | Teaser


If you want to change the fields, you can customize the Teaser in UI:

admin/structure/types/manage/article/display/teaser

Or in this node template (this targets the View, so it would also work, if you changed the view mode):

node--view--taxonomy-term.html.twig

Or switch to a field based View and configure the fields inside of the View.