Yes, you got it right, John_TN. Let me explain how it works.

You'll have to upgrade first to QuickBooks 2015 since you have the 2012 file. Next, convert it to the 2018 version, then to your QuickBooks Desktop Pro 2021. The reason for this process is to ensure your old file will not be corrupted and will work in the new version.

However, we don't have any trials for the older ones. We only have for the new one so our customers can experience the new features. You'll want to find someone who has older versions that can help you or, you can find it on the web.
 

I'll add this reference to help you upgrade your file: Upgrade your company files after you switch to a new version of QuickBooks Desktop.

Once your file is updated, you'll want to check the reports, like Profit and Loss and Balance Sheet, to ensure everything is converted.

Feel free to get back to this thread if you have more questions. We'll get back to you as soon as we can. Take care!