A lot of users that first have to deal with either .heif to .heic files 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 jpeg, you will have to download and use the free iMazing HEIC converter utility or similar program.