Why is Toolchain Not Updated with Arduino IDE Install on Mac
The boards packages maintained by Boards Manager and associated tools are installed in .arduino15 folder. The AVR boards package bundled with IDE is only used when there is no AVR boards package version in the .arduino15 folder.

To locate the .arduino15 folder open Preferences in IDE and there at the bottom of the window is displayed the location of the preferences file with full path to .arduino15 folder.

The content of .arduino15 folder is not changed with IDE update.