Hi @Mack L,
I'll start and others will probably add more.
Microsoft Edge WebView2 is enabled by default in 12.1.0 or later. WebView2 Runtime is required by Framework Manager.
You need administrative privileges to install the WebView2 Runtime.
WebView2 Runtime is also required if you plan to install Transformer. If you are wondering about what is Transformer, please go to the next line.
If you use the compatible query mode (CQM), the database client software must be installed on the same computer as Framework Manager. Database connectivity must be set up. For instance, if you are using Oracle, you need to install an Oracle client on this new virtual servers.
From IBM Cognos Analytics on Premises 12.1.x Supported Software Environments, you might need to check CQM and/or DQM:

If you are still planning to upgrade, you might want to wait for v12.1.3 (it should be available very soon). It will be the last version in v12.1.x (before v12.2.x after summer break).
Best regards,
Patrick Neveu