Disable Comments

A site wide switch that allows you to disable the WordPress commenting features entirely on post, pages and media. Disable Comments also hides the Comments menu item in the backend, and any comment related Gutenberg blocks.

Extract from WordPress.org

This plugin allows administrators to globally disable comments on any post type (posts, pages, attachments, etc.) so that these settings cannot be overridden for individual posts. It also removes all comment-related fields from edit and quick-edit screens. On multisite installations, it can be used to disable comments on the entire network.

https://wordpress.org/plugins/disable-comments/