Can I have an animation say, "Add 1 to the x position"?

I'm making a 2d VN like so: https://imgur.com/a/kClKB60 I want these characters to have many different horizontal actions. e.g., move off the screen to the left/right, both go to the left until they hit the edge and don't overlap, have one go to the center while the other stays where they are, etc. Is there a way to do this without having to come up with every permutation of what I want?

I've only figured out how to have an animation that says, "Start your x, y, and z position at (0,0,0) and change it to (-1, 0, 0)." Instead, is there a way to say, "Subtract -1 from your x"? I don't want to have to specify the starting position, and I don't want to effect the y or z in any way, nor modify it.