Creating a scale bar but for area, not length

[BarrettLewis1]

I have a map, on which I want to see a scale for acreage. Essentially I want the same thing that a scale bar does, but show area by units. This is obviously not possible with a scale bar, but how could I otherwise achieve this?

I was thinking of creating a polygon that perfectly fit the area I want to reference (100 acres). My idea was that somehow maybe I could get it to show up in the legend exactly as it is sized on the map at that reference scale, but I can't seem to do this either. How could I go about doing this?

[WilliamSmith6]

You could create a tessellation for 1 square block that represents acreage. Generate Tessellation (Data Management)—ArcGIS Pro | Documentation
Create Fishnet works in a similar way. Create Fishnet (Data Management)—ArcGIS Pro | Documentation

This may be a roundabout method, but you could then select and move the square or hexagon on your map. Or you could add it to a separate map and import it as a inset map with no basemap in your layout. That might look better.