Here is how you can enable or disable comments in WordPress post or pages If you are using old or New text editor which is block editor or classic editor.
Managing comments in block editor
When you create new post or editing post you can just disable or enable comments. While in editor you will see menu in right side there is a discussion section expand this and you will see option two enable and disable comments in your post or pages.
If you are right side menu is not visible then you just need to click on setting icon on your top right corner
Managing comments in classic editor
Like block editor while editing and creating new post you will see discussion option below the post editor if it doesn’t visible than enable this from your top menu where screen option click on it will expand make sure discussion option is check or not make sure its checked