Hello,

Sorry to say but right now there isn’t such an option available to adjust the height of the Columns under Custom Layout. Although, if you want you can select a different Predefined Layout from the available Layouts that best suits you: https://snipboard.io/JUH0KI.jpg

If you have added this Request under the Feature Request, then the Development Team will surely look through it and if they find it fits with the Theme environment then surely they will look through it.

Best Regards