Trying to understand how workflow code affects History Size of a Workflow

Lets take the above pseudo code for a workflow which invokes one activity taking a small input and returns a small output.
The Code above and below the activity invocation involves referencing the big List. Is it safe to assume that just because the big list is being referenced in both workflow tasks, the history size dramatically increases?

In other words, If I were to stop referencing the big list after the activity invocation, would my history size drop?

Limiting the inputs and outputs for an activity to reduce history size seems straight forward.
How exactly does a workflowTask contribute to history size?

The list itself is not stored in the workflow history unless it is passed to the workflow as an input argument or signal, or activity result. So in your example, the history size is not affected by the size of the myBigList independently of how it is referenced.