Stock or aftermarket radio? Some amps require 12 volts directly from the positive terminal of the battery depending on the power output and have a relay the gets a voltage from the radio to switch it on.
Ha, on a car like my 30 Olds, had to have brains to put the parking brake on, transmission in neutral, before using the handcrank or you could kill yourself. 37 Olds had a stock radio, no accessory position on the ignition, radio was always hot, had to remember to turn it off, and the headlamps as well or your battery would go dead.
But then they added an accessory position to the ignition, had to switch that on first to play the radio, did this for years, until the BCM came along. If using an aftermarket radio, have to read the instructions, one place close with a 25 amp fuse on it that only works in accessory and ignition is the power outlet. 04 Cavalier and later radios, couldn't even bench test them, need a data link from the BCM with some kind of strange digital code.
Some of this was to prevent thief like who would want to steal an OE radio. Data link on the Cruze is also used for all those vehicle functions and that ding ding for the directional signals, and as a strong reminder, you opened the door with the ignition key in the lock.
Crutchfield will help you to install and aftermarket radio and even the amplifier. Another website is Meta for installation. Depends on what you got and what you intend to do.