More information about content in Link field autocomplete dropdown? In a project we have a Link field where editors can link to internal content or external content. 

There are several cases where nodes of different content types have the same title. 

Is there a way to display more information than just the node title in Link fields autocomplete widget - so that we can make it easier for Editors to pick the right node?

We are using LinkIt but that does not support the link module at the moment.
The autocompletion matches are provided by EntityAutocompleteMatcher::getMatches. The format is hardcoded as $key = "$label ($entity_id)". Label and entity id come from selection manager, which packages entity id and label pairs in an array keyed by entity bundle, so that could be used as a source for adding content type into the results. You'll need to override system.entity_autocomplete route's controller to get to your own matcher.

The same controller is used for rendering the selection dropdown though it does not display the entity ids, only labels (in web/core/misc/autocomplete.js). Overriding that is another thing you'll need to do.