Create custom post type

cpt-element.php

<?php

/**
 * Register CPT
 *
 * @return void
 */

function clean($string) {
    $string = str_replace(' ', '-', $string); // Replaces all spaces with hyphens.
    return preg_replace('/[^A-Za-z0-9\-]/', '', $string); // Removes special chars.
 }

add_action('init', function () {
    $context = "bme";
    $cpt_name = 'Élément';
    $cpt_lowername = clean(strtolower($cpt_name));
    $dash = "dashicons-admin-home";
    $supports = ['title', 'editor', 'thumbnail'];

    $labels = array(
        'name' => _x($cpt_name, $context),
        'singular_name' => _x($cpt_name, $context),
        'add_new' => _x('Add new', $context),
        'add_new_item' => _x("Add new $cpt_name", $context),
        'edit_item' => _x("Edit $cpt_name", $context),
        'new_item' => _x("New $cpt_name", $context),
        'view_item' => _x("View $cpt_name", $context),
        'search_items' => _x("Search $cpt_name", $context),
        'not_found' => _x("$cpt_name not found", $context),
        'not_found_in_trash' => _x("$cpt_name not found in trash", $context),
        'parent_item_colon' => _x("Parent $cpt_name :", $context),
        'menu_name' => _x("$cpt_name", $context),
    );

    $args = array(
        'labels' => $labels,
        'hierarchical' => false,
        'description' => "Elements",
        'supports' => $supports,
        'public' => true,
        'show_ui' => true,
        'show_in_menu' => true,
        'show_in_rest' => true,
        'menu_position' => 3,
        'show_in_nav_menus' => true,
        'exclude_from_search' => false,
        'has_archive' => false,
        'capability_type' => 'post',
        'menu_icon' => $dash
    );

    register_taxonomy(
        $cpt_lowername . '-' . 'category',
        array($cpt_lowername),
        array(
            'hierarchical' => false,
            'label' => 'Categories',
            'singular_label' => 'Category',
            'show_in_rest' => true,
        )
    );

    register_taxonomy(
        $cpt_lowername . '-' . 'tag',
        array($cpt_lowername),
        array(
            'hierarchical' => false,
            'label' => 'Tags',
            'singular_label' => 'Tag',
            'show_in_rest' => true,
        )
    );

    register_post_type($cpt_lowername, $args);
}, 10);