custom_post_type_event.php

function my_custom_post_event () {
    $labels = array(
        'name'               => _x('Event', 'post type general name'),
        'singular_name'      => _x('Event', 'post type singular name'),
        'add_new'            => _x('Add new event', 'event'),
        'add_new_item'       => __('Add new event'),
        'edit_item'          => __('Edit event'),
        'new_item'           => __('New event'),
        'all_items'          => __('All events'),
        'view_item'          => __('View event'),
        'search_items'       => __('Search events'),
        'not_found'          => __('No events found'),
        'not_found_in_trash' => __('No events found in trash'),
        'parent_item_colon'  => '',
        'menu_name'          => 'Events'
    );
    $args = array(
        'labels'          => $labels,
        'description'     => 'Event description',
        'public'          => true,
        'menu_position'   => 29,
        'capability_type' => 'page',
        'hierarchical'    => true,
        'rewrite'         => true,
        'supports'        => array('title', 'editor', 'thumbnail', 'page-attributes', 'revisions'),
        'has_archive'     => true,
        'menu_icon'       => 'dashicons-admin-post',
        'show_in_rest' => true,
    );
    register_post_type( 'event', $args );
}

add_action( 'init', 'my_custom_post_event' );

function my_taxonomies_event_type () {
    $labels = array(
        'name'              => _x('Event category', 'taxonomy general name'),
        'singular_name'     => _x('Event category', 'taxonomy singular name'),
        'search_items'      => __('Search event categories'),
        'all_items'         => __('All event categories'),
        'parent_item'       => __('Event category parent'),
        'parent_item_colon' => __('Event category parent'),
        'edit_item'         => __('edit event category'),
        'update_item'       => __('Update event category'),
        'add_new_item'      => __('Add new event category'),
        'new_item_name'     => __('New event category'),
        'menu_name'         => __('Event category'),
    );
    $args = array(
        'labels'       => $labels,
        'hierarchical' => true,
    );
    register_taxonomy( 'event_type', 'event', $args );
}

add_action( 'init', 'my_taxonomies_event_type', 0 );