Adding classes to all links of a given type, on a certain field, in modern Drupal

Not sure i’m describing this well— the point is for the sitebuilder / developer to easily add classes used in theming to links.

We could add link classes to ClassItUp, so at least there would be a class to hang styles on, where currently there is none. But really we want to be able to add classes that make semantic sense and fit into frameworks, like btn for Bootstrap or button for Bulma.

The Link Class module does almost everything i need:

It’s primary use is allowing people entering content to provide a class on a link, but it can also be configured to automatically apply classes and not bother content editors with a choice that’s between the site builder and the themer, in many cases.

The problem though is that this still works at the moment of saving, so any existing links do not get updated— so adding a class to all links provided by a given field is not going to work as expected