I think this is impossible, because in line or bar chart on X axis you have dimension not an expression. For example in scatter chart you can add vertical reference lines because there is an expression on X axis.
You can add vertical reference lines IF you can use a continuous X axis. Attached is an example. Select different test types to see low and high limits specific to each type of test.
As another possibility, you may be able to put regular old lines or boxes beneath your chart if your chart size won't change. You can conditionally show them if they differ based on other information. Attached is an example with different reference boxes for employees and customers.
