Unfortunately, the (needed to play .hevc or .h265 files in apps like Windows Media Player or Photos) are not legally available for free from Microsoft.
Here is the correct situation:
Microsoft sells the standard "HEVC Video Extensions" in the Microsoft Store. It is a paid license due to patent royalties.
Some devices (Dell, HP, Lenovo, etc.) include a specific "HEVC Video Extensions from the Device Manufacturer." This is only free if your computer came with it pre-installed. You cannot download that version manually for free.