How to create a multilayered 2D effect?

So the idea I want to go with is some sort of Paper Mario depth effect where you have your scene with multiple layers going in the background.

However I can’t seem to get the layers to interact with each other. What I would ultimately like to do is have your front scene, have an extra layer with mountains or what have you and make the character be able to go there.

Layer 1 is the front where most of the action takes place.
Layer 2 is “further away” than layer 1 but still walkable for the player. Essentially you have to think of there being a bridge going from layer 1 to layer 2 but the tricky part is to have the sprite itself go smaller in size due to the fact that he is going further and deeper into the scene.

Is this even possible? And if so, how would I go about doing this?
If I’m not making sense, please feel free to let me know, I’ll try to explain as best I can.

Ahaha ! I know what you’re talking about, it is very clear 'cause I’ve played Super Paper Mario :wink:

Theoretically it should be quite easy to do, and I guess there is many ways to reach this. The first one that came to my mind :

Each layer should have it’s own collider/set of colliders. De-activate colliders on the layer you leave. Activate the collider on the layer when you arrive on it.

Scaling a sprite is not a problem, you can also choose to change it with a smaller one.