As of macOS Monterey, there's a new Quick Action in Finder called "Convert Image". You can select all the images files you want, including HEIC images, and then Ctrl-click and choose Quick Actions > Convert Image. Then you'll get this dialog:

[![enter image description here][1]][1]

[![enter image description here][2]][2]

Super simple to convert these from Finder now.

  [1]: https://i.sstatic.net/syVoE.jpg
  [2]: https://i.sstatic.net/usMux.png