How to obtain a walkable area greater than the underlying object?

Hi all,
I am using a Recast Graph. I would like to create a walkable area over objects (e.g. planes, cube, …) greater than their top surface. My purpose is to make the character falling when oltrepassing the edge of the underlying object.
Is there a simple method to create a walkable area (e.g. a Recast Graph) affected by an offset beyond the underlying object?
I have tried setting a negative character-radius but it is not permitted.
Anyone can help me?
Thank you in advance!

Anyone could help me please?


You could have an invisible collider that you include in the rasterization process.
Alternatively you could do the same thing with a mesh. Just ensure that you put it in a layer that is not visible to the player.