When transfering an image from the iPhone to the Mac, it comes in the .heic file format. This is a new format that is not supported by all applications. Oftentime, another format (such as jpg) is required to further make use of those images.
Since I was not able to find a useful tool to do this on my computer, I decided to roll my own: heic-to-jpg.
The program itself is not too spectacular. Essentially, this is just a thin wrapper around imagemagick's convert cli. What is nice about it, though, is that it seems to be useful for other people as well. The repository has been receiving some stars and forks, and I have received some nice feedback from people who have been using it. The other day, I even received a pull request from someone who added a new feature to the tool.