Allow paid or application Iframing in HTML under custom domain.

I want following URL

" https://9000-idx-studio-1746517181632.cluster-htdgsbmflbdmov5xrjithceibm.cloudworkstations.dev/?monospaceUid=935650 "

under my customer domain. Easiest way is Iframing in index.html and put it under custom domain.

deployment is so tough i tried all day.