I can help you with creating another company for your QuickBooks Online.
You'll need to sign-up for a new QuickBooks Online account to create another company. One company file is equivalent to one subscription.
To put this company under your existing Intuit ID, log into your current company when creating a new account. Simply click on the Add another company button when creating another account (I'll be adding a screenshot for reference). From there, you'll only be asked for an Email address and Password (you should be using the same email address).
Once done, you can easily switch from one company file to another. Kindly refer to this article for the detailed steps: How do I switch companies?.
If you wish to learn more about the things you need to do with your new company, you can visit this article link for the detailed information: Learn QuickBooks basics and get set up for success. It contains topics and subtopics that are very helpful in setting up your company.
Please let me know if you have other concerns. I'm just around to help.