How to Create a Simple Child Theme that Completely Disables Discussion Forever

Good Afternoon, everyone. I think everybody knows by now that WordPress has evolved from a blogging platform into a content management system. For many websites, the discussion features are not only irrelevant, but they are also an unnecessary headache. I have read a bazillion posts over the last few years, explaining half-baked solutions to disabling comments on a WordPress site. Some of the posts are so old, you almost need the Wayback machine to read them. So this has been a long-needed feature in WordPress. I have yet to encounter a satisfactory solution.

I would post this topic in the feature request forum, but since others have been doing the same for at least a decade, with little or no response from the WP team, I have to assume they are not interested in implementing a “disable discussion” button. The current discussion settings page is convoluted and doesn’t prevent bits and pieces of the commenting system showing up in unexpected places. You also can’t use it to disable past commenting. I also know you can use a plugin, and I have tried that, but I would rather just use a child theme.

This is what I need to do:
COMPLETELY AND FOREVER, disable discussion functionality and any reference to it on my website, past and future. I would like to have a fairly simple, plugin-free solution, that I can implement (preferably in less than 15 minutes,) in a child theme, and forget about it.
I have the latest version of WordPress installed with the latest version of Parabola theme to date, but it would be best to have a theme neutral solution.
If anyone could offer a simple way to add a “disable discussion” function to a child theme, I would be grateful. If it includes creating or editing PHP files, please explain fully, as I have very limited coding skills, as do many others who might be looking for a similar solution. Thank you.