how to do html validation and backend validation together in laravel code example

Example 1: if any error in blade laravel

@if ($errors->any())
     @foreach ($errors->all() as $error)
         <div>{{$error}}</div>
     @endforeach
 @endif

Example 2: laravel validation

/**
 * Bootstrap any application services.
 *
 * @return void
 */
public function boot()
{
    Validator::extend(...);

    Validator::replacer('foo', function ($message, $attribute, $rule, $parameters) {
        return str_replace(...);
    });
}