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.