If you have a Developer Apple Account (even the free tier) and use Xcode on Mac, then you can pair a Mac to Apple TV, and through that you can set the Apple TV box to Developer Mode, which adds a few extras in Settings. One such extra is the on-screen overlay (“Playback HUD”) with stream details. The Playback HUD doesn’t change or configure anything, but it shows the resolution, codec, bitrate, etc. It doesn’t support all apps in my experience (notably not the YouTube app), but more than just Apple’s own apps (e.g. HBO Max is supported).
I don’t subscribe to F1 TV, so I can’t do the actual step for you for this content provider and show the result.
But if they advertise to bring 4K to Premium subscribers, then I have no doubt that such is what they are streaming (for non-archival content). They have the infrastructure to bring it, and a reputation to protect by delivering exactly as promised. I don’t think the on-board cameras are top tier from what I have seen, though. Some segments of the live race just show the limits of miniature cameras.
It should be easy to visually see if it is 4K, as the races have static text on screen most of the time, which would be maximum smooth in 4K, or show text artifacts from upscaling if so processed.
… match range screen for match resolution so my external video scaler could do the upscaling …
Modern mid-tier and higher TVs do excellent upscaling, set-top boxes like Apple TV do excellent upscaling. I see no reason to even consider a stand-alone video scaler for regular viewing, unless some of the other equipment in this setup was proven inadequate to do this step. Feels like chasing that last imperceivable 0.01% improvement.
