How to set the height of CK-Editor 5

 The editable area html as bellow - 

<div class="... ck-editor__editable ck-editor__editable_inline ..."> ... </div>

So you can write css for change editable area height. 

You can write css as bellow -

.ck-editor__editable_inline {
    min-height: 400px;
}

OR

.ck-editor__editable {
    min-height: 500px;
}