How to move comments section out of its parent div
Depending on which container you want to escape, you need to use either node.html.twig (recommended) or page.html.twig (harder, unlike node you can't use {{ content.field_comment }} in page).

If you are using node.html.twig (or somehting like node--BUNDLENAME.html.twig) and you manually render {{ content.field_comment }}, then you can avoid double-rendering of comments by rendering the "normal" content using the without filter {{ content|without('field_comment') }}