Tesla destination EVSE will have a cord to reach the vehicle and a Tesla connector. The Tesla destination connector uses the same J1772 communication protocol to communicate with the vehicle. Adapter just changes the shape of the connector to fit non-Tesla vehicles. Electrically it is just the same.
No you cannot change the the signal without opening the Tesla wall box.
If the I-Pace does not work at the 48 or 80 amp setting... this is another defect in the I-Pace charging protocol system. Any fully compatible J1772 vehicle should charge fine from 6 amp to 80 amp signal.
I speculate 48 and 80 are fairly common as the supply is very common to be 60 and 100 amps and these run at 80%.
No harm should come to the vehicle... will apparently just fail to start charging. I do not actually have an adapter, nor have I actually used a Tesla destination connector.