How does Truesight affect a shapechanger who grows/shrinks like a polymorphed dragon?

Question

In searching for this answer, I did come across this post that is similar, though my question is more cosmetic than functional...

The sense of Truesight states:

A monster with truesight can [...] perceive the original form of a shapechanger or a creature that is transformed by magic.

Many dragons, such as the Ancient Bronze Dragon have the action:

Change Shape. The dragon magically polymorphs into a humanoid or beast that has a challenge rating no higher than its own, or back into its true form.

I've always thought of True seeing as simply seeing things as they are in this regard, as seeing the white complexion of a changeling. However, while observing this trait from the dragon, something occurred to me that seems odd:
A wyrmling is a medium size, meaning there might not be much hight difference, but an ancient dragon is Gigantic, meaning their true form would be quite massive

So trying to visualize how this would seem tends to create certain issues:

• The size of a dragon being now smaller could fit into spaces a large dragon could not
• If the dragon used a form with additional limbs, such as a spider, would those appear to the creature with Truesight?
• Given the size difference, how would one aim for the dragon?

Given that, I am wondering How would Truesight work on such a creature whos size changes, such as the dragon? Would they see a tiny dragon 6-7 ft tall? or be staring into space as they talked to it?

Another example of this is a polymorphed Tyrannosaurus... Would the truesight creature gain a disadvantage on the creature's attacks, only seeing the person within?

Answer 1

Truesight sees both

Many animals can see into the ultraviolet. What does that look like? I have no idea because humans can’t see it, and we have no conceptual touchstone to describe what color ultraviolet is.

Similarly, I don’t know what it looks like to see the shape changed creature in both it’s changed and unchanged forms. But someone with truesight does. Truesight simply does what it says: they can perceive both at the same time, and that makes sense to them just like binocular vision makes sense to me but would be meaningless to a cow.

Let's be clear about what truesight does:

• "see in normal and magical darkness" but doesn't allow them to tell the difference between normal and magical or that an area is dark although that can probably be deduced from the absence of light sources.

• "see invisible creatures and objects" but would not alert them to the fact that other creatures can't see them although, again, this may be obvious from context.

• "automatically detect visual illusions and succeed on saving throws against them" with effects that depend on the specific illusion. Most allow people who have saved to 'see-through' them while still "seeing" the illusion. Some are special, like Mirage Arcane which allows the truesight enabled to choose whether to interact with the reality or the illusion.

• "perceive the original form of a shapechanger or a creature that is transformed by magic" so they see what everyone else sees but they "perceive" the original as well and they can tell their difference.