Tutorial is not done yet, those generally wait for the final release before beginning so can grab the final UI etc.
Render settings/General settings/Upscaling
For final renders, set how you want the AI Upscaling to be used. Disabled is default as you don't want to use it in finals. You can set it to Only Sequences if you want it to apply to final renders of animations only (and single, still images will not use it), or Always so that it affects final renders of stills or animations. This is for producing drafts, four times faster (but with loss of detail).
Preferences/Interactive rendering/ Image upscaling factor
This has always been there and is not new in Corona 12 Update 1. It does not use AI Upscaling, it simply makes an IR image twice as large (or three times as large, etc.) As a result, the image will be pixelated and blocky. It's for faster IR on large screens (4K etc) without having to run IR at a large size.
Render setting/Performance settings/Interactive rendering/Use upscaling
This is a similar thing to the previous option, except it is new and does use AI Upscaling. This applies only to IR and not to final renders. If enabled, the image is rendered to one half width one half height then AI Upscaled, so it renders four times faster, but does not look pixelated - but does lose detail.
