C:\Program Files (x86)\Microsoft SQL Server\140\DAC\bin>
SqlPackage.exe /Action:Extract /SourceDatabaseName:"DBName" /SourceServerName:"DBServerName" /SourcePassword:"password" /SourceUser:"username" /p:VerifyExtraction=False /p:ExtractReferencedServerScopedElements=False /p:IgnorePermissions=True /p:IgnoreUserLoginMappings=True /TargetFile:"C:\export_directory\SchemaFileName.dacpac"