if you are playing with your friend on the same local network, port forwarding is not required. However if both of you are in different network, port forwarding of the host will be required:
How to port forward:
If you are using a phone, you can play with your friend by opening a hotspot on your phone and ask your friends to connect to it. This should form a local area network (LAN) and allow connection between the devices. I don't think you even need to enable data for LAN connection to work.
Of course your friend must be 8n the range of your hotspot
If you can host a hotspot it maybe works, but you cannot port forward on mobile data. Instead you can join the Discord to find a list of servers.