Custom Post Type

<?php
function create_portfolio_post_type() {
    $labels = array(
        'name' => 'Portfolio',
        'singular_name' => 'Portfolio Item',
        'add_new' => 'Add New',
        'add_new_item' => 'Add New Portfolio Item',
        'edit_item' => 'Edit Portfolio Item',
        'new_item' => 'New Portfolio Item',
        'view_item' => 'View Portfolio Item',
        'search_items' => 'Search Portfolio',
        'not_found' => 'No portfolio items found',
        'not_found_in_trash' => 'No portfolio items found in trash'
    );

    $args = array(
        'labels' => $labels,
        'public' => true,
        'has_archive' => true,
        'publicly_queryable' => true,
        'query_var' => true,
        'rewrite' => array('slug' => 'portfolio'),
        'capability_type' => 'post',
        'hierarchical' => false,
        'supports' => array('title', 'editor', 'thumbnail', 'excerpt'),
        'menu_icon' => 'dashicons-portfolio',
        'show_in_rest' => true
    );

    register_post_type('portfolio', $args);
}
add_action('init', 'create_portfolio_post_type');