Can i update ios16 by cellular data?

You can do it only if you're using a 5G connection and your cellular carrier authorized that activity.

Shouldn't be this case, to perform an update procedure wirelessly, you need to connect your device to a reliable and fast Wifi Network with internet access (no cellular data, unless you use a 5G network, no personal hotspot on your device, no VPN connections, no low power mode are admitted). AND I suggest that you keep the device plugged into power during the whole update process.

If you don't have a wifi network with Internet access, "borrow" one from your relatives/friends/neighbors, or ask for help at an Apple Store or Authorized Service Provider or Authorized Reseller.

Do not forget to create a full backup of your device, before any updates.

Regards

Giulio

Yes, if your carrier supports 5G, your iPhone 12 Pro can download and update without using Wi-Fi. However, you must still be aware that there must be at least 50% battery left on your iPhone in order to be able to update.

If you want to download an update with 5G, you must activate Allow More Data on 5G. Activate here:

Settings > Cellular > Cellular Data Options > Data Mode