Can I fly my dji mini 3 pro (rc-n1) without cable that needs controller that connects to the phone to use the dji fly app?

No  you cannot do that.  RC needs the connection to the mobile device (thus the FlyApp).

cheers
JJB

No but you can without using the app.

Hi there. We appreciate you for reaching out to DJI Forum. We strongly recommend using the DJI Fly app on your mobile device when flying the aircraft to ensure safety and also for you to maximize the feature available on the DJI Fly app. Being said, the mobile device needs to be connected to the remote controller using a supplied USB cable. However, you can still use the aircraft with a remote controller only but the functions are limited also it is not recommended for safety purposes. Thank you for your understanding and support.