If I am working with objects that are small in real life, but in the Unity world they are scaled larger, should I increase the Gravity with the scale of the objects?
For example, if an object of size one would actually be 10 cm across, would gravity scaled to be 10x make the object behave more like a small object would in real life.
I know objects fall at the same rate, but the rate is the same so small objects fall more in proportion to their size don't they?
The Unity default gravity of 9.81 units / second² assumes that one unit is one meter and the game takes place on Earth.
If these assumptions are not true, you would theoretically have to adjust it accordingly. If one unit in your game is actually just 10cm, then you would have to increase gravity to 98.1 in order to be physically correct.
But the question is: Do you actually want the gravity in your game to be physically correct? Human intuition often has a wrong idea of how gravity acts on objects which are very large or very small. People intuitively expect that a humanoid character grown to the size of a skyscraper or shrunk to the size of an ant would move and fall just like a regular sized person in regular gravity, even though that would not be the case.
So keeping the gravity at the default value might actually feel more correct to your players even though it is not. And besides, even games which are actually meant to have a realistic scale and realistic physics sometimes adjust the gravity. Because even though 9.81 m/s² is correct in theory, it might still feel wrong in the context of a particular game. Sometimes gravity is changed globally, sometimes just for specific objects (the jumping mechanics of player-characters in particular rarely obey the laws of physics). The only way to find the perfect gravity value for your game is rigorous playtesting.
I am looking forward to playing your game.
I dont't think there is an objectively correct answer to your question, in the sense that it is up to how you feel it should feel. It is ok and not uncommon to tweak the gravity scale as well as any other physics parameter of your game engine in order to provide a more satisfactory game experience.
To make a small example, say that your small object is a rock and you want to throw it. Perhaps with gravity scale set to 1 the throw will not look so cool or fast, but if you increase the gravity scale it will have a faster fall, simulating an heavier object. On the other hand, if the object that is falling is a feather, you should reduce the gravity scale to have a slower fall. It's an iterative process: try different values until you find the one that fits the effect you were looking for.
