.NET Standard and Multi-targeting Corrado Cavalli on January 16, 2019 I've recently blogged about multitargeting in .NET Standard libraries, what do you think? (dont' shoot the pianist... 😊) link to blog post here
Something else that can be helpful is conditionals around <TargetFrameworks> and <PackageReference>. Similar to ItemGroup, PackageReference also takes a Condition attribute.