Seems like your normals are smoothed across the edges anyway. To isolate the normals from any lighting influence and make sure, you could switch the viewport to buffer visualization > world normal, the surfaces should be a single flat color. If there’s a gradient then somewhere in the conversion from blender to unreal the hard edges were lost.
I personally don’t use blender, but there are plenty of people who do, so there must be some documentation to find out which step in the export/import process caused your issue.