The default WordPress comments might look something like this:
Let’s say you instead want to give an option for the user to post comments using Facebook.
To do so one needs to add a plugin. I came across to which I tested.
https://wordpress.org/plugins/gs-facebook-comments/ and https://wordpress.org/plugins/comments-from-facebook/
As I planned to use the plugin for a Norwegian site I discovered that Comments from Facebook – WpDevArt Social comments has a field to where I could choose which language pack to use.
I noticed that after having installing and activating Wpdevart Social comments that a new FB comments showed up on the left WordPress sidebar.
Login to your account or create a new account here:
https://developers.facebook.com/apps
Go to my Apps. Then Add a New App.
After having created the App. The next screen will show various Add a Product options.
I took the App ID (be sure to add your own App ID) and I pasted into the first option inside the plugin Comment settings. I then went through and adjusted the various options I wanted to change. Clicked Save and then checked one of the posts.
As you can see above with what I typed. Click into the box and the option to click the checkbox Also post on Facebook shows up.
Turn off default WordPress comments.
If you want to turn off default WordPress comments. That can be done by going to Settings -> Discussion -> uncheck: Allow people to submit comments on new posts
Resources:
https://www.wpbeginner.com/plugins/how-to-install-and-setup-facebook-comments-in-wordpress/
https://www.themeum.com/how-to-add-facebook-comments-to-your-wordpress-site/
Plugins:
https://wordpress.org/plugins/gs-facebook-comments/ and https://wordpress.org/plugins/comments-from-facebook/