In WordPress page, post, archive page, search page, blog page etc. have their own design. Sometimes there are custom page templates included just as FrontPage template of Royale News. When we create posts or pages they are displayed with their own designs. We can not modify them. If you need new kind of design, it must done creating a page template. As you have mentioned, you need a page displaying posts from one category and similar to blog page, it needs a custom page template.
I hope you get your answer. If you have any questions, do ask.
Here are few links that might help you further :
- Support : Go support page
- Themes : Go check themes
- Theme Documentation : Read theme documentations
- Blog : Read blog
If your problem has been solved with the response, do kindly mark post as solved & rate profile 🙂