Welcome to the Community. I'd be glad to help provide information about using QuickBooks Online.
Unlike the desktop version wherein you install the program locally on your computer, creating a copy in QBO is unavailable. Please know that the system automatically backs up the data with the same level of security from financial institutions.
As a workaround, you can make a conversion to QuickBooks Desktop then move it back to online again. However, doing this process has some limitations on what will include on the migration.
For more insights, I recommend visiting the support articles I'm adding on this: