use the latest version of the .NET Framework that's supported by the release of Exchange you're installing.
Exchange Server 2016 CU23 Any supported
OS .NET Framework 4.8
Install the .NET Framework 4.8.1 Offline Installer [English] (prior to installing any added language packs).
Download From Here: https://dotnet.microsoft.com/download/dotnet-framework/thank-you/net48-offline-installer
Note: In the Server Manager console, when checking the features that are installed on Server 2016, only Dot Net Framework 4.6.1 is installed (2 of 7 features).