How do I modify the "Formats" dropdown in CKEditor The CKEditor in Drupal 8 has a Formats toolbar button containing different text formats: "Heading 1", "Heading 2" etc. How can I add and remove items from this list?
I would use Styles instead of Formats, because styles are fully controlled by you, from admin interface, no need for editing files.

When you add it to the toolbar you can configure it and add as many elements as you wish.

Here is an example config: