Greetings from Syncfusion support.
We have checked your query at our end. By default, our Rich text editor component height is set based on content. Please find the below sample for your reference.
If you want to specify the height for Rich Text editor, you can use our height property. Please find the below API link.
Could you please share the below details?
a. Please share the code and replication procedure for this issue.
b. If possible, please make the video for understanding the issue.
Please let us know, if you have any concern on this.