In CKEditor 4 to change the editor height there was a configuration option: config.height.
How do I change the height of CKEditor 5? (the Classic Editor)
Use max-height and min-height both. Beacuse max-height give scroll bar option after reached maximum mention height. Where min-height give static height to .
max-height
min-height
.ck-editor__editable { max-height: 400px; min-height:400px;}