ArcGIS Pro 2.9.5; color JPEG
Scenario: Click a raster layer in the Contents pane > Symbology pane > Primary symbology > Classify

As far as I can tell, Classify will only be available in the picklist if the raster layer is grayscale, not color. It's possible to create a dynamic raster grayscale layer using Raster Functions. But that's a multi-step process. As a novice, it would be great if the Symbology pane could automatically convert the raster to grayscale and therefore support the Classify symbology method.
Also, the documentation doesn't specify that Classify only works on grayscale. Could the docs be enhanced to include this information? https://pro.arcgis.com/en/pro-app/latest/help/data/imagery/symbology-pane.htm
Related: Why is Primary Symbology > Classify unavailable for some images?