How to Copy File and App Icons Using macOS Preview
The article explains how to use the macOS Finder's Copy command to copy file icons into Preview. Instead of using the Paste Item(s) command, you can open the Preview app and select File->New from Clipboard to create an image of the copied file's icon. This method works for apps and known file types with system icons in macOS. For PDF files or alias files, additional steps may be required to obtain the generic icon image.