Hi Sudip,
From the provided details and screenshot, we can understand that your requirement is need an UI interface to edit/customize chart in RichTextBox control, like Microsoft Word. We will add this scenario to the feature request and consider this requirement while implementing the below feature.
Now, you can now track the status of your request, review the proposed resolution timeline, and contact us for any further inquiries through below link.
If you require this functionality in provided workaround application, you can try creating custom UI interface and add it with below workflow, to edit/customize chart.
1. On insert chart, open custom UI interface with predefined set of chart templates using WPF SfChart control
2. On click insert in that interface add UI container with SfChart into RichTextBox control
For more information about WPF SfChart control, you can refer our UG documentation from below.
Regards,
Ramya T