About Logic Pro X Track Stacks

Hi Everyone,
I am learning that track stacks are a good way to make layers stack of instruments or sounds on one another in real-time

My question is since all their layers are all mash together how do you get more separation
From what part of the layer you want to hear
or donot want to hear
Meaning let say you have 4 layers
And you want to hear different parts of layer 2 to come through
I hope this make any sense

How would you do this in Logic