I would recommend to signup for 2 new QBO accounts for this purpose. Then consider to purchase a 3rd party service to migrate your data or use a migration tool.
Allow me to elaborate or clarify things so you can get back to working order, info.
A QuickBooks Online (QBO) subscription is designed to record and account transactions for one business. You will need to create separate account for each company so you can run their own reports.
Don't worry! You can also use the same login credentials, so you only need to switch between companies.
To do this, go to the QuickBooks pricing page and select the subscription option you want. This will route you to any if these two experiences:
If you're signed in to QBO, you’ll be asked to confirm the account you want to sign in with. If the account displayed is the one you want to use for the new company file, select Yes, that’s correct.
If you haven’t signed in recently, you’ll be asked to create an Intuit account. Don't fill this out unless you want to connect your new company file to a new account. Instead, look for the Adding a company to an existing account? section and select the Sign in link. Sign in with the user ID and password you already use for QuickBooks.
Follow the on-screen instructions to create a new company file. After that, every time you log in to QBO, you'll be ask which company file you want to open. To switch between companies when you're in QBO, select Settings ⚙ and then Switch company.