Add a Custom Type to WordPress, and show it in GraphQL

functions.php

<?php

add_action( 'init', function() {
  register_post_type( 'events', [
     'show_ui' => true,
     'labels'  => [
       'menu_name' => __( 'Events', 'your-textdomain' ),//@see https://developer.wordpress.org/themes/functionality/internationalization/
     ],
     'show_in_graphql' => true,
     'hierarchical' => true,
     'graphql_single_name' => 'Event',
     'graphql_plural_name' => 'Events',
  ] );
} );

add_filter( 'register_post_type_args', function( $args, $post_type ) {

	if ( 'events' === $post_type ) {
		$args['show_in_graphql'] = true;
		$args['graphql_single_name'] = 'Event';
		$args['graphql_plural_name'] = 'Events';
	}

	return $args;

}, 10, 2 );