Setting symbology using Apply Symbology From Layer tool
The Apply Symbology From Layer tool can be added to the end of a model to control the symbology of the model output. This technique is only valid when the model output variable is a feature layer, raster layer, TIN layer, or Network Analysis layer. For example, a feature class variable cannot be connected to the Apply Symbology From Layer tool. First, use the Make Feature Layer tool to convert the feature class to a feature layer, then connect the feature layer variable to the Apply Symbology From Layer and apply a symbology from an existing layer. There are equivalent tools to create raster, TIN, or Network Analysis layers from data on disk.
Model output symbology can also be set using the Layer Symbology property. Setting symbology through the Layer Symbology property may be more straightforward than using the Apply Symbology From Layer tool, since it does not require the addition of extra processes to the model. Using both techniques to define model output symbology is redundant.