To get the game running in a full-screen window, you'll want to start up the app, load up SimCity and set the game to run in windowed mode.

The change primarily impacts old DX10 and DX11 games running in Windowed and Borderless-Windowed mode. Modern games using DX12 already benefit from this. That said, Microsoft has cautioned that: ...

The optimizations can also “significantly improve latency” for older games running in windowed mode, according to Microsoft. New optimizations for windowed games feature in Windows 11.