A warm welcome to the Community, @ksprack. You can upgrade to the QuickBooks Desktop 2024 version from 2021, and I'll share more info.
Yes, all 2021 versions of QuickBooks Desktop will be discontinued by May 31, 2024. It includes certain services like Payroll, Payments, live technical support, Online Backup, Online Banking, and critical security updates protecting your data starting June 1, 2024.
Intuit is planning to stop selling new subscriptions to fresh customers after July 31, 2024. Since you're interested in upgrading to the Plus 2024 version, it would be best to do so before that date. To purchase and verify the cost, you can look for the Sales contact number in this article: Can't buy QuickBooks Desktop as a new US subscriber.
Once subscribed, you won't be affected by the discontinuation in May 2024 because you will be billed yearly. Additionally, the Plus subscription offers features like enhanced security, efficiency, and more. To learn about the available functionality, visit this page: New and improved features in QuickBooks Desktop Plus 2024.
You can also see this page for the details and price: Buy QuickBooks Desktop Plus.
Please know that you can always get back to this thread if you need further assistance performing QuickBooks tasks on your newly subscribed company. It'll be my pleasure to help you. Have a great day!