1. Any drone is fully capable to fly with the remote controller that comes with the drone. Don't need a phone to do that.
*** there is exception*** Tello is meant to be flown by a phone. Remote controller is optional and does not come with the drone.
2. The only reason using a phone is to be able to connect to the drone's camera so that one can see what the drone's camera sees.
3. When they say it is a 5G drone, they actually meant to say it is a drone with a camera that is 5G WIFI transmission.
4. A 5G Wifi drone needs a phone that supports 5G wifi transmission in order to receive the images transmitted from the drone's camera.
5. A phone that is equipped with wifi 802.11ac will be able to receive transmissions from the 5g wifi drone. Without the wifi 802.11ac , a phone is useless for a 5G wifi drone.
In summary, 5G phones means a fifth generation 'phone. As davidhk129 said, 5G means 5GHZ WiFi (sometimes known as WiFi 5), nothing to do with 5th generation 'phones that work with 5G 'phone masts. The key is the 802.11ac standard, in the 'phone's specs.