Which file is used to store layer symbology in ArcGIS Pro?

In ArcGIS Pro, the file format used to store layer symbology is the .lyrx file. This type of file contains the symbology settings for a layer, including the color, size, and style of the features being represented. It allows users to save their custom symbology settings and easily apply them to other layers or share them with others. The .lyrx file format supports a wide range of symbology options, making it a versatile and powerful tool for visualizing geographic data effectively.

On the other hand, .sty files are used in ArcMap and are not compatible with ArcGIS Pro, while .mapx files are intended to store map document information but do not specifically handle symbology. The .symb file format does not exist in the context of ArcGIS. Thus, the .lyrx file is the correct choice for storing layer symbology in ArcGIS Pro.