I agree child themes would be a good way to continue to update themes while keeping any custom changes separate however we didn’t do this to begin with so I don’t know if I can create a child theme after the fact.
Thank you salsaturation for your points as well. I agree that many of these themes are at risk of security threats because of all the functionality they build into it to avoid use of plugins.
Is there a way to turn an existing theme that has been installed into a child theme? Even if the theme was installed a year or 2 ago and has not been updated since?