.iso vs .cdr format? My Macbook Pro optical drive is out of commission.

If I use my sister's Windows 10 or Windows XP to make an ISO file from a DVD and bring over by sneakernet, will I be able to play it as a DVD?

Or can it be converted to .cdr?
macOS will recognize both an .iso, .cdr and .dmg (for that matter) as a standard disk image. 

Copy it to the Mac and double click on it and it should mount on the desktop and recognize it as standard DVD...

...ASSUMING that the DVD does not have some copy protection built-in that will prevent a simple disk image copy. Unfortunately that is likely and you may want to look into Windows compatible software that will enable copying commercial DVDs.