I found a workaround that involves using d8.jar get d8.bat functionality. Actually d8.bat is just a helper file which calls d8.jar provide its functionality.

STEP 1: locate d8.jar. Its found under SDK\build-tools\30.0.3\lib\d8.jar

STEP 2: use java to call d8.jar.

Syntax:

java -cp <path_to_d8.jar> com.android.tools.r8.D8 <D8_arguments>

Refrences:

1. Stackoverflow answer 1
2. Stackoverflow answer 2