Add do follow to links

Here’s a doc explaining how: https://ultimateblocks.com/add-nofollow-links-in-wordpress/

I know this method but this is not solve my problem.

In the past we didnt set a nofollow attribute to older links so they are do follow.

If i activate this plugin: https://www.ads-software.com/plugins/wp-external-links/ i can set all external links to nofollow, but if i want a do follow link in an article i need to add to the excluded links (in the plugin settings) and this is time for our editors to do that. So that why am i asking.