how to load Normal files using composer autoloader

How to load normal files using composer actually psr-4 loader classes along with namespaces I know but if we have normal files inside that function for example if have functions and arrays so how can access arrays from that file like this

<?php 
  $default = ['controller' => 'welcome','method' => 'index', 'params', [] ];
  function myFunc(){
       echo "My func function!";
  }
 ?>