Following the Sign Your App Manually guide,
You can sign your app from the command line using standard tools from the Android SDK and the JDK
apksigner
shipped with Android SDK Build Tools 24.0.3 (see https://developer.android.com/studio/releases/build-tools.html). The tool can be found in the Android SDK's build-tools/<tools version>
directory. For example, build-tools/24.0.3/apksigner
on Linux/OSX and build-tools/24.0.3/apksigner.bat
on Windows.
Use This command will work for sure (For Windows)
--Go to this directory C:/Users/{UserName}/AppData/Local/Android/Sdk/build-tools/29.0.0/
--Type this command : apksigner.bat verify {PathToApp/AppName}.apk
Full Example :C:/Users/Surya/AppData/Local/Android/Sdk/build-tools/29.0.0/apksigner.bat verify C:/AndroidApp/test.apk
On Windows 10 it should be under directory
C:\Users\{user}\AppData\Local\Android\Sdk\build-tools\
Note the AppData directory is by default hidden. First make sure you installed Android SDK 24.0.3 or later.
On mac
The Apksigner is inside build tools all you need is this line
/Users/adewale***/Library/Android/sdk/build-tools/28.0.3/apksigner verify MyApp.apk
just change /Users/adewale***/Library/Android/sdk/build-tools
to your build tools path.
Done