Carousels hold attention longer than a single picture, and each swipe tells the platform the post is worth showing. They suit steps, lists, before-and-after and stories with a turn.
The first slide works as the hook and the last as the call to action. Keep every slide in the same shape: Instagram crops them all to the shape of the first.
Example
A hair studio's carousel: slide one “From box dye to copper in one visit”, then four photos of the process, then “Book a colour consultation”.