Remark: I work at CKEditor as a Developer Advocate 🥑

Drupal 12 is in beta since DrupalCon Rotterdam, and today both official CKEditor contrib modules got their matching 2.0.0-beta1 releases:

• CKEditor 5 Plugin Pack 2.0.0-beta1
• CKEditor 5 Premium Features 2.0.0-beta1

What to know before you try them:

• 2.x requires Drupal 12 and is not compatible with Drupal 10 or 11. The 1.x line stays for Drupal 10.3+ and 11.
• Both modules have to be upgraded together with core, in one Composer operation:

``` composer require \ 'drupal/core-recommended:<sup>12.0@beta'</sup> \ 'drupal/core-composer-scaffold:<sup>12.0@beta'</sup> \ 'drupal/core-project-message:<sup>12.0@beta'</sup> \ 'drupal/ckeditor5_plugin_pack:<sup>2.0@beta'</sup> \ --no-update

composer update --with-all-dependencies ```

• Already on Drupal 12 without the modules? Then just composer require 'drupal/ckeditor5_premium_features:^2.0@beta' 'drupal/ckeditor5_plugin_pack:^2.0@beta'.
• Both betas switch to the CKEditor 5 UMD installation method that Drupal 12 uses. Premium Features also adds a collapsible AI container, AI Chat context configuration, configurable heading levels in the document outline, clipboard mode for collaboration, and Arabic-Indic numbering for footnotes.

I tried to kick this off a bit during DrupalCon Rotterdam, the slides give the high-level idea of the 1.x vs 2.x split: CKEditor in Drupal: News in Content Editing

Are the release notes clear? If anything in the upgrade path is confusing or breaks on your Drupal 12 test site, say it here and I will pass it on to the module maintainers.