For now here is how you do it. This requires Novella or other themes that support Aesop full width components.
Go to you edit post page on backend. Choose Text mode for editing.
And you enter your iframe code like this:
What’s important here is that you make sure you set the width to 100%, AND you don’t hit enter before your iframe tag. If you hit ENTER WordPress will insert a tag which prevents iframe going full width. Let me know how it goes. Thanks.