To know about the steps for , you should check the steps mentioned below:
Move to the desired post on the profile for which you want to restrict the comments.
Click on the three-dot option from the top-right corner of the post.
Click on who can comment on your post.
After this, choose one of the three options that are listed as friends, public, and profile and pages that you mention.
Lastly, follow the given available option and restrict people from adding comments on the Facebook post.