If you would like Facebook to prioritize the display of the most relevant comments on your public posts instead of listing them in a chronological order, you simply need to enable Comment Ranking on your Facebook Page.
When Comment Ranking is enabled, the comments that receive a greater number of Likes or Replies will be placed higher on the list.
This guide will teach you how to enable Comment Ranking on Facebook.
Display the Top Comments First on Facebook
Sign in to Facebook, go to Settings > Followers > Comment Ranking and click on Edit:
Next, click on the drop down menu next to Comment Ranking and select On: