KT-MyPage/app/Http/Controllers/PDFController.php

<?php

namespace App\Http\Controllers;

use App\Kintone\Models\Receipt;
use App\Logic\ReceiptManager;
use PDF;

class PDFController extends Controller
{
    public function entry()
    {

        $manager = new ReceiptManager(2);

        $file =  $manager->makePdf();

        $receipt = $manager->getReceipt();

        // キントーンへの保存
        $receipt->setFiles(Receipt::FIELD_RECEIPT_PDF_FILE, collect([$file]));
        $receipt->save();

        return response()
            ->file($file->getFullPath());
    }
}