In Google Play Console I came across
App size savings using the Android App Bundle-
Your app could be 38.4% smaller if you used the Andro
App bundle now avalaible in Visual Studio 2019 v.16.2
I generated Android App Bundle in xamarin using Developer Command Prompt Visual Studio 2019 v.16.2
msbuild -restore XamAndroidApp.csproj -t:SignAndroidPackage -p:Configuration=Release -p:AndroidKeyStore=True -p:AndroidSigningKeyStore=filename.keystore -p:AndroidSigningStorePass=password -p:AndroidSigningKeyAlias=keyAlias -p:AndroidSigningKeyPass=password
Follow this link for more infos
Hope this help someone