Hi Debbie Watkins,

recently I developed the same features for copy website design/style into a New Website, to just select Parent Website in a Newly website created, so it will copy it into a Newly create a website with multi-company.

it needed small customization for achieving that result.

Thanks & Regards,
Sunny Sheth (shethsunny555@gmail.com)

It depends on how you have done your styling. If you did it the proper way by creating or overriding css/scss classes in a separate scss-file and by properly appending it to the website assets, you can easily use this file on any other website.
If you have done it by adding classes to qweb views manually or even worse, by using inline styles, you can obviously not copy it. In this case I recommend you to collect all style edits and do like mentioned above.