Can I restore my whole company in QBO Plus from my backup I made before?

The ability to restore a company file is currently available to QuickBooks Online (QBO) Advanced subscriptions. This functionality is not supported within QBO Plus, Kristina.
 

In QBO Plus, you can either enter the data manually or import it. Here's how to import:
 

1. Go to the Gear icon.
2. Select Import data.
3. Click the box on the data you will import.
   
4. Follow the on-screen instructions.
    

On the other hand, you can consider upgrading your subscription to QBO Advanced to gain the ability to restore your company at once.
 

You can always revisit this thread if you have additional concerns.