How to Add Quicktags in WordPress Comment Forms
By default the WordPress comment box does allow basic html tags, but most bloggers don’t’ know that and most commenters don’t know html. So what is a quicktag? Well this is a quicktag its a button that users can use to easily and quickly style their comments.
To get that on your site, install and activate the basic comment quicktags plugin.
Then to go Settings — > Discussion.
And click activate quicktags for comments.
Save your changes.
Now your commenters will have these quicktags to use while responding to your posts.