Appearance → Customize → Archive → Feature the first post. Off by default, because it rearranges the top of every listing you have.
What it does
The newest post in the listing is printed above the rest as a hero: the image on one half, the headline, excerpt and meta on the other. The rest of the listing continues underneath, without that post repeated.
+--------------------------+--------------------------+
| | CULTURE |
| image | The bridge that took |
| | forty years |
| | Two councils, three ... |
+--------------------------+--------------------------+
+---------------------------------------------+--------+
| The next story | img |
+---------------------------------------------+--------+
+---------------------------------------------+--------+
| And the one after | img |
+---------------------------------------------+--------+
The hero and the archive header above it run the full container width, not the reading column, whatever width the listing below uses. That is what makes it read as a lead.
The image side follows Thumbnail side — set it to Left and the hero flips with the rest of the listing. On a phone the hero stacks image-above-text, where sides mean nothing.
Where it applies
Only where a lead makes sense:
| Blog home / posts page | yes |
| Category, tag, author, date, CPT archive | yes |
| Page 2 onwards | no — the “newest” post there is arbitrary |
| Search results | no |
| 404 | no |
Per category or tag
A category can overrule the site setting for itself. Edit the term — Posts → Categories → a category → Edit — and use Feature the first post:
| Inherit from Customizer | the default; the site setting decides |
| Yes — feature the first post | this archive leads with a hero even if the site does not |
| No — plain listing | this archive stays flat even if the site leads |
The field is on categories and tags. A plugin can add it to a custom taxonomy with the stoat_term_featured_taxonomies filter.
That gives you the usual news-site arrangement: a hero on the front page and on News, a flat list on Corrections and Obituaries.
When it is the only post
If the listing holds exactly one post, it becomes the hero and nothing is printed underneath. There is no empty list and no stray rule.
When to use it
A hero is a claim that one story matters more than the others. That is true on a news front page and on a magazine section, and it is usually false on a personal blog, where the newest post is simply the newest. If your posts are equal, leave it off.