Many mods should use ModCheck and some of them even contain Its library in their files.
For Example: Vanilla Animals Expanded — Livestock

Ah ok! so they just hide it in their files. no need to install it eh? alright.

It's still better to just include it explicitly, as I just lost a bit of time trying to fix the error "Internal failure patching Verse.LoadedModManager.ApplyPatches" that kept popping up every time I started Rimworld with a certain mod ("bridges"). Turns out that this is a result of that mod bringing with it an older version of ModChecker.
Putting this mod before the "Core" module solved that error message.