It's always mentioned in DJI's manuals. So whenever you buy a new DJI product, it's a good idea to download the manual from their website and get familiar with all the details about your new device.
If you bring up the radar display showing the drone and homepoint in relation to the RC on the RC or phone screen there is an indication of the strongest signal link shown by the drones icon changing color. Strong link is green, weaker link is blue.