Hello bonniemac,
It's great to hear that the business is now incorporating! That's an exciting time for a business, and I can appreciate needing to close out the old books before moving on. I'm happy to help by highlighting a feature you can consider for closing out the inventory in QuickBooks Online.
When you mentioned needing to close out the old inventory in QuickBooks Online, the feature that jumped to mind is the Adjust Inventory feature, which allows you to change the quantity on hand in the books. This may work for your situation. You can learn more about it here: Adjust inventory quantity on hand in QuickBooks Online
If you're not sure that does what you need it to or would still like to use a journal entry, I recommend checking in with other accountants to see what they recommend. As a tech support agent, I can't advise on the type of journal entry to use or the accounts to target with it, although I can share this article about journal entries in the software should you need it: Create a journal entry in QuickBooks Online
Luckily, there are accountant users and bookkeepers here in the QuickBooks Community that may be able to help you out. Keep an eye out for responses from them to see if anyone has anything in mind for you.
If you're not an accountant, but would like to work with one, check out the My Accountant tab in QuickBooks Online. That tab has a Find a pro to help button, which is a handy tool for finding QuickBooks-certified accountants near you.
Wishing you the best with this!