Many people that encounter .heif to .heic files for the first ime wonder how to open them on their Windows machines or convert them to some common format like JPEG (.jpg, .jpeg). Whilst you can easily view or convert these files on Mac, HEIF format (uses both .heif and .heic) are not natively supported in Windows.
In order to convert heif to jpg, you will have to download and use the free iMazing HEIC converter utility or similar program.