I have ArcGIS Server feature services published from Arcmap and it's a registered geodatabase on the Arcgis server. I'm thinking of moving the contents to Pro, and I'm wondering if I have to republish from Arcgis Pro even if it's a registered geodatabase in ArcGIS Server. I'm afraid that the republishing might change service Urls, please guide me on how to with less hassle. Thanks
Assuming you have a standalone GIS Server (No Portal), I don't think you need to republish the existing map/feature services, unless there is desired change in attribute schema or layer properties.
*Note: Unlike ArcMap, in ArcGIS Pro, you can publish Map/Feature Services to a standalone GIS Server site only.
Connect to a GIS server—ArcGIS Pro | Documentation
Publish a map service—ArcGIS Pro | Documentation
Overwrite a map service—ArcGIS Pro | Documentation
Thank you @JayantaPoddar . Please clarify - if I don't republish from Pro, will the source data (for feature and tiled services) will still be pointing to ArcMap? What should I do to make it point to Pro ? Since ArcMap is retiring soon, I would like to move the contents to Pro.