Thank you for posting here in the Community space. I can provide clarification about entering purchase orders in QuickBooks Online.
The option to create multiple purchase orders at once is unavailable in QuickBooks. You can look for a third-party app and follow the recommendations of @Fiat Lux - ASIA.
Here's how:
On the left navigation bar, click Apps.
Use the search bar to find an app.
Press the Enter key.
View the results.
In QuickBooks, you can also update the status of a purchase order and add it to a bill or run a report. Here's the link you can visit for your reference of the process: Create and send purchase orders in QuickBooks Online.
Let us know if you still have more questions about creating purchase orders by leaving a reply. Take care, and have a great rest of the day.