It is possible VR makes some difference but, here's briefly how LODs in GSX objects are made:
We used multiple LODs, from a minimum of 3-4, to the maximum allowed of 10, averaging 5-6 LODs per object. This will ensure the lowest fps impact and the lowest memory footprint. The MSFS SDK has a diagnostic tool, which tells us exactly when LOD must switch, according to what Asobo evaluated as be the maximum allowed, depending on the object visible size on screen. The tool will tell you exactly where to stop, showing a "green" value if you are correct, a "yellow" value if you are approaching the maximum allowed, and "red" if you are wrong, meaning your object is too complex for its size, so you must switch to a lower LOD.
This changed after SU5 and, back then, Asobo announced in the future, all products that won't conform to this, will have their objects removed automatically. They said these rules would have been entered in effect only after several months, lots of developer complained because there weren't used to make many LODS, this scared so many developers that I think as of today, the full rules never entered into play ( they possibly are on the Xbox, not sure ), and has been replaced with a "milder" version, that is removing anything if it's less than 0.5% of its original size. Nobody really cares of this.
But, we decided to stick to the rules entirely, because they are helpful for us, knowing when we are wrong, which sometimes is not so obvious. Since we need to display lots of different objects at time, and keep the fps impact as low as possible, we applied the rules to the max, so almost all our objects are always "in the green", meaning all our LODs are correct as Asobo requested. If the full rules would eventually enter in effect, not many products other than GSX ( and possibly our KCLT ) will still work...but that's not likely to happen, because of that, and because that announcement about LOD enforcing made many developers to enter in panic mode, since adding multiple LOD levels to everything, costs time and work and money.
The LOD levels in 3d objects ( NOT TERRAIN! ) is controlled by the Object LOD slider. We tuned the LODs with the slider at 100, which is used by default in "HIGH" settings. Ultra, by default, is 200, meaning all the object's LOD will be doubled, and Medium by default is 50, so all LOD will be halved.
That's to assure you how all LOD has been made to conform completely to Asobo recommendations about fps and memory allocation and (with a few exceptions for vehicles that always appear alone, like the Deicer ), they all pass the "green" text in the Dev Tool.
And, the slider you can use to tweak them is the OBJECT LOD, which is completely separate from the other LOD, that is the Terrain LOD.
VR is a completely different matters, because of the circular rendering, so it's possible we might even need a different set of objects (only their XML files! ) with LOD levels retuned for VR.
