First of all it is good to know, that when creating a new format it will look like the latest edited format.
But you can save time and effort by creating a new form based on a previous made. See the steps below and find out how.
Open up "Formats" in the left menu.
Click on the format you want to duplicate.
Type in the new format in width and height.
Click on the small arrow next to "Create new format" and click "Create from selected format".
Happy building 👏