Is it the same fix for a p2757 on a toyota corolla 1010?

Question

The dealership said I need a new alternator without even opening the hood. Just based on the code.

Answer 1

P2757 Torque convertor clutch pressure control solenoid control circuit performance / stuck off

A faulty charging system will not necessarily set a transmission code. If the charging system is not performing as expected that should be resolved, Low charging system are known to cause all types of code to be set.