I needed to submit some heic photos to a service that only accepted jpg. I didn't know about the heic format, but a little searching gave me a solution:
bash
$ heif-convert
bash: heif-convert: command not found...
Install package 'libheif' to provide command 'heif-convert'? [N/y] y
...
$ find . -iname '*.heic' -exec heif-convert -q 100 {} {}.jpg \;