I have a layer file which I use as reference for symbology for future layers. It is based on unique values, however there is over 100 unique values, and each one have their own icon.
If I apply this symbology to a small layer, its legend or symbology table will have over 100 items, even if the layer only uses 3-4 symbols. I wonder if there is a way (through Python preferably) to remove all icons that are not been used in that layer.
ArcGIS Pro has a button called Add Unlisted value, and I'm looking for the exact opposite: remove all unlisted values.
In ArcGIS Pro, try checking the "Only show features visible in the map extent" box, which can be found under Feature Display Options menu. This will make it so that only things that appear in the current map extent are displayed in your legend.