Done a bunch of researching and it seems that 3rd and 5th gen'rs have a key fob combination to change the buzzer volume. As far as I can tell, the buzzer volume on a 4th gen can only be modified via mechanic and would cost around $50.

How to remove lock/unlock buzzer on a 2005 4th gen 4Runner.

The buzzer is a piezo located in the back of the engine bay, on the driver's side, right under the hood support strut, on the inside of the wheel well.

Open the hood and locate the driver side hood support mounting point (1.)


Underneath that, you can see a wire going through a hole that leads to the front left wheel well (2.)


You need to take out the plastic ring (2.) (good luck). The buzzer is fastened to the inside of the wheel well by a plastic clip (4.), disconnect that by squeezing it.



Once you pulled the buzzer out (5.), disconnect it (6.) and set the devilish thing on fire *insert pitchfork emoji*. Seal the end of the clip (6.) with duct tape and fasten it to some of the adjacent wires.