Regarding changing the color of the captionbar, Yes. it is possible.Please go through the knowledge base article
How to draw a custom caption for docking windows?
Regarding changing the height of the captionbar, we had created the feature request.Here is the link to track the status of the feature request implementation.
Feature Request #1188 - Ability to change the height of the captionbar
Thanks for choosing Syncfusion products.
Regards,
Murugan P.S