A page can be copied and used as a basis for a new page to preserve its design.
To copy a page, go to the Pages tab on the editor's right side. The pages of your site appear in the site's navigation menu and are displayed in a list.
From your list of pages, click on the three-dot icon "..." or double-click on the page you want to copy.
Click on Duplicate to create a copy of your page.
The copied page will be added to the end of your list of pages by default.
From there, you can Rename it.
You can also choose the page's position as either a main page or a subpage.
To learn more: How to change the order of my pages?