Is there a way to calculate geometry with GSS or how can I change this project to PCS?
Use the tool from ArcToolbox and specify your desired projected coordinate system
Calculate Geometry Attributes (Data Management)—ArcGIS Pro | Documentation
It seems that your data is at a local level. The best practice is to project your data to a suitable projected coordinate system (PCS) using the Project tool:
https://pro.arcgis.com/en/pro-app/latest/tool-reference/data-management/project.htm
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