The clouds there use light propagation but there are grid artifacts and low sampled aliasing. I also can't see how many layers those clouds are made of because you can't go up to them.Not to put down FS2020 but what's advanced about the lighting that you haven't seen in other games that you wanted to see for years?
I'm pretty sure driveclub did volumetric clouds and light propagation 7 years prior:
The lighting in FS2020 uses a significant number of GI light probes that are highly accurate and change every few km (think of AC:Unity x10). They are sampling a very accurate representation of the sky with the clouds being a part of that environment lighting approximation. You could get rain clouds with rain a few thousand feet horizontally away from you while the sun is shining directly above where you are and the direct+GI lighting is accurate.
Their clouds have physical behavior in that the wind is used with heat from the surface for convection and go through the entire cloud lifecycle from accumulation, mature and dissipation stage. Some clouds displaying the upside down anvil in the mature stage just like in real life.
Their use of texture synthesis (using a procedural noise and baking it down to a texture map) has never been done in any game. It's been very prevalent in the film industry and is a very complicated pipeline.
I could do a full graphics analysis on FS2020 but it would take way too long to make trying to explain things.