Implicit `using static` - where to declare it?

Hello.
I have a utility class and I’m using it in 99% of the code. I want to get rid of using static Utility.Extensions in every file.
I tried going to project properties in MSVS for a possible option but they’re not available.

I’m pretty sure that you can’t do this (unlike, for example, in Visual Basic where the equivalent thing is possible).

See for example, this 2015 proposal for such a feature: Proposal: Project level using statements · Issue #2044 · dotnet/roslyn · GitHub

The responses in that link include reasons why it wouldn’t and shouldn’t be done.

Note also that even if you could find options in VS or Monodevelop that enabled it, that wouldn’t in itself enable Unity to compile your code.