Hi again,
If you add the footer content using the Dashboard > Appearance > Additional CSS area, you won’t lose the changes when the theme is updated.
However if you prefer to make a child theme, feel free to do so.
After I create the child theme, my understanding is that I was forced to modify the footer.php file
You aren’t forced to since you can use CSS instead. However, you can make changes to the footer.php file in the child theme, and the changes will remain even if you update the parent theme.