make a global php function in laravel so that accessed anywhere
function your_function( $parameters ) {
    //function logic
} 
function your_another_function( $parameters ) {
    //function logic
} 
// composer.json
"autoload": {
    ...
    "files": [
        "app/Helpers/your_helper_function.php"
    ]
    ...
}
// Now call from any class of Laravel
class UserController extends Controller {
   
  public function storeUser() {
  	your_function();
    
    // do other stuffs
  }
}
