Changing Post Layouts in Archives

Hi there

I’m quite new to WordPress (actually very new) – is there any plug-in that can change the layout of the archives for each category so that the whole post is not just displayed one after the next? We have some quite long articles and it would be more user-friendly if maybe just an image, a header and a quick introduction to each article could be visible, and then a user could just click on the header to read the full article. I’ve searched the plug-ins with a variety of search terms but I haven’t found anything that seems to offer that kind of functionality?