Curious why you would need one? They dont have a typical drain plug with a crush washer. Its a half turn plastic plug with an o-ring. If it isnt damaged the o-ring may need replacing now and then but it should be fine otherwise.
If you truly need one here is one source.
2019-2021 GM Drain Plug 55498782 | Chevy Direct Parts
If you truly need one here is one source.
2019-2021 GM Drain Plug 55498782 | Chevy Direct Parts