Editing polygon line thickness when using "Bivariate Color" symbology in ArcGIS Pro

Question

Question summary

How can I vary the thickness of the edges/lines of polygons when they are symbolized using the "Bivariate Colors" option?

Explanation, context and what I tried

When I symbolize a polygon layer using the "Graduated Colors" symbology option, I can edit the thickness of the polygon's edges/lines using the "Format all symbols" item inside the "More" drop down menu.

However, when I symbolize a polygon layer using the "Bivariate Colors" symbology option, I simply cannot find a way to edit the thickness of the polygons' lines/edges.

I've tried all of the sub-menus, but wasn't able to find out where this can be edited. I even tried a workaround of using the "Vary symbology by attribute" and setting a constant value, but that didn't work either:

Software version

I'm using ArcGIS Pro 2.9.3.

Answer 1

If you want to change thickness of all edges you click on the template icon

Here is an example of setting the border on a bivariate colour scheme to a gradient stroke for a cool effect.

I don't think you can change the thickness of individual colour scheme polygons, well I've not worked out how.