Excel Sparkline charts don’t have a horizontal axis. Here is a technique that creates one in the cell above or below the Sparkline. This works best for the Column Sparkline.
A Sparkline chart is a single data series chart (graph) that exists in a cell. Usually, you only need to select one range to create a Sparkline. Sometimes you may need to handle missing dates.
I am not a fan of Merged Cells but there may be a case to use them when creating a larger Sparkline chart.