Files to Delete ?

Yes they are, HEIC / HEIF means High Efficiency Image File Format. Just like JPEG and PNG... They are just lossless images... HEIC being the "container" holds both Image and video information.

If you are not sure if you want to delete them just go to the folder they are located and open them with Preview or Photos...

HEIF are image files and look to be Wallpaper images. Being part of the MacOS installation I’m inclined to leave them in place.

As the Title in image above states " Sort through documents and Permanently erase files you no longer need " If not needed in the future - yes remove them