Meta Box

<?php
// CREATE CUSTOM FUNCTIONS FOR RESTRICT FIELDS
function cmb_fields_by_user_role( $fields ) {
    $current_user = wp_get_current_user();
    $user_roles   = $current_user->roles;

    $filtered_fields = array_filter($fields, function($field) use ($user_roles) {
        // If the field does not have the 'cmb_role' key, we include it by default
        if (!isset($field['cmb_role'])) {
            return true;
        }

        // Checks if one of the user's roles is in 'cmb_role'
        foreach ($user_roles as $role) {
            if (in_array($role, $field['cmb_role'])) {
                return true;
            }
        }

        return false;
    });

    return array_values($filtered_fields); // Reindex array
}

// EXAMPLE METABOX FIELDS
add_filter( 'rwmb_meta_boxes', 'register_example_fields' );
function register_example_fields( $meta_boxes ) {
	$meta_boxes[] = [
        'title'        => __('Custom Metabox'),
        'id'           => 'custom-metabox',
        'post_types'   => ['cpt'], // CPT
        'fields'       => cmb_fields_by_user_role([
            [
                'type' => 'text',
                'id'   => 'field_1',
                'name' => '<h3>Field 1</h3>',
				'cmb_role   => array(administrator')
            ],
            [
                'type' => 'text',
                'id'   => 'field_2',
                'name' => '<h3>Field 2</h3>',
				'cmb_role   => array('author','administrator')
            ],
            [
                'type' => 'text',
				'id'   => 'field_3',
                'name' => '<h3>Field 3</h3>',
				'cmb_role   => array('administrator')
            ],
        ])
    ];

    return $meta_boxes;
}