Sample
:github : arcgis-pro-sdk-community-samples\Map-Authoring\CIMExamples\ChangeLayerDataSource.cs
In the final with ChangeUSHighwaysLayerDataConnectionAsync
MapView.Active.Map.SaveAsFile($@"C:\Data\Admin\AdminSample.mapx", true);
The relative path to the layer data source is not correct in AdminSample.mapx after saving
ArcGIS Pro Version : 3.0.2