How to create a page that shows posts from multiple categories

Question

looking to create a page that will show all posts from several categories. for example lets say I want all of my posts from category 1, 5, and 9 together. the posts on the page should be ones from any of those categories and aren't required to be in multiple of them or all of them. is it possible to do this?

Answer 1

To display a custom query in a single page you would need to create a new page template and assign that to a page.

1. Create a file in your theme's main folder and call it multiple-categories.php

2. Paste the following code in the file

   <?php
   /* Template Name: Multiple Categories */
   
   get_header();
   
   $args = array(
       'cat' => '1, 5, 9',
       'posts_per_page' => -1,
   );
   
   $my_posts = new WP_Query( $args );
   
   if( $my_posts->have_posts() ){
       while( $my_posts->have_posts() ){
           $my_posts->the_post();
           //Echo the post
       }
   }
   wp_reset_postdata();
   
   get_footer();
   

3. Create a new page and in the template field select "Multiple categories".

Visiting that page you should see the articles from any of those categories. The template file and name is just an example and can be changed at will without using the default ones listed here https://developer.wordpress.org/themes/basics/template-hierarchy/

More details about the arguments for the query relative to categories can be found here: https://codex.wordpress.org/Class_Reference/WP_Query#Category_Parameters