Hello,Can I open a new account under an existing account ?

Hey there, @turnert625.

Can you help me verify what account are you trying to open in QuickBooks Online? 

If you are looking to set up a new QBO company account under the same Intuit account, you can subscribe to a new plan in QuickBooks. Each company file requires its own paid subscription, but you can access them using the same login details. This allows you to seamlessly switch between companies for more efficient management.

To add a new company, visit our QuickBooks pricing page and select the subscription option you want. This opens one of two experiences:

• If you're already signed in to QuickBooks, you'll be prompted to confirm the account you wish to sign in with. If the displayed account 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. Only proceed with this if you intend to link your new company file to a new account. Instead, locate the Adding a company to an existing account? section and click the Sign in link. Enter the user ID and password you already use for QuickBooks. Then, follow the on-screen instructions to create a new company file.

Then, follow the on-screen instructions to create a new company file.

To switch between companies when you're in QuickBooks, go to Settings ⚙ and then Switch company.

For additional reference, you can check out this article: Create or add another company file to QuickBooks Online.

If your query pertains to something else, please let me know by replying to this thread. I'm here to assist you. Have a great day!