I have a QGIS (3.16) map layout (maps generated using Atlas) that I have created a map inset, which shows the full extent of the state. Within it, I have an "overview" frame that shows the actual location of the map on the overview. However, because the individual map is so small, the red overview square is nearly invisible at the statewide scale (in the overview).
How can I use a Geometry Generator to expand (maybe buffer?) the bounds of the map frame (red, map canvas) shown within the overview map? I don't want to change the actual map bounds (a rectangle), just the depiction of it within the overview map.
Edit: After doing some experimenting, I've noticed that both Simple Fill and Centroid Fill are working, but Geometry Generator is not. So I've broken it down to the simplest possible object (the polygon centroid). Now I'm thinking I might just be having an issue with choosing the right "geometry variable" to use in the to Geometry Generator. I have tried $geometry, @atlas_geometry, and @map_extent, and even @map_extent_center, without success