Hi Pete,
You got that right, landscape will be streamed in real time - and can be cached locally - mainly based on satellite images, with quite a bit artificial intelligence to make it look right on top:
(Go forward to 2:10 in order to get right to the AI landscape building explanations)
Add to that, there are 341 "photorealistic" cities where substantial parts have been modelled in 3D from real pictures:
https://se7en.ws/all-341-photorealistic-cities-in-microsoft-flight-simulator-2020/?lang=enFurthermore, all major airports contain buildings made "from scratch" to represent the airports well.
So in total, even without any addon packs, you get a fairly well modelled world that looks cool, from distance at least.
For instance when I fly over my own house, the whole street and building arrangement is fine.
Nevertheless, they didn't always get the stories right and the rooftops are sometimes off, but that really doesn't matter when we're talking about the effect that you get when flying over an area that you actually know. It simply looks "right" from above and that's what counts.
The addons I've mentioned simply add further detail "on top", handcrafted instead of generated from satellite images.
EGLC London City Airport adds Physically Based Rendering representation of London City Airport and surrounds plus a bit more.
Landmarks London City Pack adds hundreds of iconic buildings and landmarks in PBR representation, basically objects not included in FS 2020's default PBR set.
Nevertheless, even without these addons London looks great and of course you can fly from/to EGLC without them too, it's just that the addons add even more handcrafted detail on top where blackshark's AI generated landscape comes too short when you're frequently flying there.
Mike