Scott Nelle

WordPress lets you set a number of days after which comments will be unavailable for individual posts. This plugin will allow you to keep commenting open on specific posts.
Once the plugin is enabled:
<ul>
<li>Set a comment deadline in Settings > Discussion using the “Automatically Close Comments…” option. Closing comments on old posts is a great way to avoid spam comments.</li>
<li>Edit an individual post on which you’d like to keep discussion open indefinitely and check the Override Comment Deadline box.</li>
</ul>

Override Comment Deadline

Allows you to enable comments on posts which are older than the comment deadline set in discussion settings.

Dante Campbell

The DMN (Hush) plugin provides an easy way to disable comments on all post types in WordPress, including posts, pages, and custom post types. This is useful if you do not want to allow comments on your site, or if you want to disable comments for a specific period of time.
The plugin also removes all options related to comments from the WordPress dashboard, including the ability to enable comments on individual posts or pages. This helps to simplify the dashboard and prevent any confusion for users who may not be familiar with WordPress.
The DMN (Hush) plugin can be easily activated and deactivated from the WordPress dashboard, and requires no additional configuration or setup.

DMN (Hush)

The DMN (Hush) plugin allows you to disable comments on your WordPress site.

Override Comment Deadline vs DMN (Hush)