Emphasizing current time step by showing a marker or plot gradually with time (when x axis is not time)

I want to show the plot data chart next to the render view by emphasizing the current step on the plot curves.
This can be done with a time marker when the x axis is time, but is there a way when plotting not against time?

But what is the “current step” when its not plotting against time ?

Imagine that the element has force and displacement data that can be plotted against time. But how can I plot force against displacement, which is a common output?