Get pagination work on custom post type word press by setting the posts_per_page manually

custom_post_type_pagination.php

<?php
/**
 * We are hardcoding the value of the posts per page for custom post type
 * Please only change if you know what you are doing.
 * 
 * IF you found the other way you can change it.
 */
function custom_posts_per_page( $query ) {
if (!is_admin() && is_archive('newsroom') && !is_year())
        $query->set( 'posts_per_page', 15 );
}
add_filter('parse_query', 'custom_posts_per_page');


/** On other example*/
function num_posts_archive_project_ie($query) {
    if (!is_admin() && $query->is_archive('financials') && $query->is_main_query()) {
            $query->set('posts_per_page', '-1');
   }
    return $query;
}
  add_action( 'pre_get_posts', 'num_posts_archive_project_ie' );

?>