This isn't new information. I learned how to do it from here. But, I'm recording this because I have trouble finding that link. And maybe someone else will come across this and it will be useful.

#! /bin/bash
set -eou pipefail
shopt -s nocaseglob

b=heic-bkp
mkdir "$b"
for f in *.heic; do
  convert "$f" "$(basename $f .HEIC)".jpg
  mv "$f" "$b"
done