Yes, you can, userrakeshd.
To make it easier to switch between accounts, please sign up using the same email address. This helps you see both accounts when you log in.
Here's a sample screenshot of what it looks like:
For adding the new company, you can visit out website here: QuickBooks pricing page. Then, select the subscription you want to sign up. This opens one of two experiences:
Here's a sample screenshot:
You can also read this article for more information: Create or add another company file to QuickBooks Online.
Once you're signed up, you can now switch companies.
Please see sample screenshot below:
Aside from switching companies, you can also open a different supported browser and log in the other account.
I'm also adding this link with all the video tutorials to get started with QuickBooks Online: QuickBooks Video Tutorials.
If you have more questions regarding adding a company in QuickBooks Online, please let me know in your reply. I'd be glad to answer them. Have a great day!