Update WPGraphQL Endpoint URL

You can modify the WPGraphQL endpoint in code with the following:

function my_new_graphql_endpoint() {
  return 'cutepuppies';
};

add_filter( 'graphql_endpoint', 'my_new_graphql_endpoint' );

This will change the graphql endpoint url from /graphql to /cutepuppies

This also updates the WPGraphQL settings page:

WPGraphQL Settings page with updated endpoint url