You cannot do it just with the tools that smartthings provides. I think smartthings support can tell from their side. Some people get a separate device and use the mapping tool that comes with that and then they can see what the repeaters are on their network, but I wouldn’t do it just to answer this question.
The other way to do it is just with a range results test. Take a battery powered zigbee sensor and place it about 3 m away from the relay on the side away from the hub. Do a network heal so that the sensor is probably using the relay as a repeater. Pick up the sensor and start walking, checking the mobile app every 15 m to see if the sensor activity is still being detected. When you’ve moved out of range, note the location.
Walk back to your starting location and leave the sensor there. Take the relay off power (not just turned to off status, but actually off power all together). Now walk the same path that you did the first time. If the sensor had been using the relay as A repeater, the range should be significantly shorter.
Obviously this test can be affected by the other devices on your network, so it’s not always a certain diagnostic, but it usually works pretty well.