Download Operating System Recovery Image

I don't know, but there is nothing special about that ISO. Don't be mislead into thinking it has all the Alienware goodies on it.
 
You might as well just get it from Microsoft  Download Windows 10 

Having a service tag will not allow an OS download for any OS any Dell.

Windows XP, VISTA, 7, 8  ISO's are not available.  Even Microsoft has removed the Digital River ISO downloads.

Embargo countries are also Not allowed especially North Korea, Russia,  EMEA and INDIA.

You havent said

1. Which OS

2. Which model dell

3.  Which country

4.  If your warranty is still in effect.

Unfortunately To get started VIA Microsoft , you MUST have a license to install Windows 10. You can then download and run the media creation tool. You don't have a COA Sticker with KEY written on it.  Microsoft makes vendors put this in the bios.  You can retrieve the key from bios but that requires running windows.

The good news is that if you have a bios key you can borrow home or pro usb flash drive or OEM dvd and install and it wont ask for a key.

Amazon.com: Microsoft Windows 10 Home 64 Bit System Builder OEM | PC Disc 

There are generic keys but these wont allow the media creation tool to work.

Windows 10 Home:
    TX9XD-98N7V-6WMQ6-BX7FG-H8Q99
   

WIndows 10 Pro:
    VK7JG-NPHTM-C97JM-9MPGT-3V66T
   

Windows 10 Home Single Language
    7HNRX-D7KGG-3K4RQ-4WPJ4-YTDFH
   

Windows 10 Enterprise:
    NPPR9-FWDCX-D2C8J-H872K-2YT43

it is possible to install Win 10 with MS Media Creation Tool created USB Drive and you don't need any Generic Key.

there is only one Thing you should know. what was installed before, Pro or Home Version? then create the USB Device with the correct Windows Version.

during Installation

click on "I Don't Have a Product Key" and proceed with the Windows Setup.

now you have Windows running and it:

a) activates itself

b) can be activated after you figured out the Product Key for your old Windows Copy.

3 Ways to extract the Windows 8 Product key from the BIOS