CPT

<?php

/**
 * Gallery custom post type
 */
function register_custom_post_type() {
  $labels = [
    'name'               => 'Galleries',
    'singular_name'      => 'Gallery',
    'add_new'            => 'Add New',
    'add_new_item'       => 'Add New Gallery',
    'edit_item'          => 'Edit Gallery',
    'new_item'           => 'New Gallery',
    'view_item'          => 'View Gallery',
    'search_items'       => 'Search Galleries',
    'not_found'          => 'No Galleries found',
    'not_found_in_trash' => 'No Galleries found in trash',
    'parent_item_colon'  => '',
    'menu_name'          => 'Galleries'
  ];
  $args = [
    'labels'              => $labels,
    'public'              => true,
    'exclude_from_search' => false,
    'publicly_queryable'  => true,
    'show_ui'             => true,
    'show_in_menu'        => true,
    'menu_icon'           => 'dashicons-images-alt2',
    'query_var'           => true,
    'rewrite'             => ['slug' => 'gallery'],
    'capability_type'     => 'post',
    'has_archive'         => true,
    'hierarchical'        => false,
    'menu_position'       => null,
    'taxonomies'          => array( 'category' ),
    'supports'            => ['title', 'editor', 'author', 'thumbnail', 'excerpt', 'custom-fields']
  ];
  register_post_type('gallery', $args);

}
add_action('init', __NAMESPACE__ . '\\register_custom_post_type');