Laravel has a nice filesystem abstraction that allows you to easily save files to any filesystem. It works by configuring a "disk" in config/filesystems.php and then using the Storage facade to interact with that disk.
Laravel PDF can save PDFs to any disk you have configured in your application. To do so, just use the disk() and pass it the name of your configured disk.
Here's an example of saving a PDF to the s3 disk.
use Spatie\LaravelPdf\Facades\Pdf;
Pdf::view('invoice')
->disk('s3')
->save('invoice-april-2022.pdf');