The Delphi IDE Colorizer plugin now is compatible with RAD Studio 10 Seattle. This new version includes support for the new IDE enhancements like the Community toolbar, Object inspector filter and the Code navigation toolbar (Castalia).
The next screenshot shown the RAD Studio 10 Seattle IDE styled with the Onyx VCL Style.
(click to get a full size image)
You can get more info of the plugin in the github site.
Remember report any issue or suggest a new feature using the issue page of the project.