It mostly depends on how tight you want the coupling between your project and the dependency in question. It can vary between just getting the source files and

It mostly depends on how tight you want the coupling between your project and the dependency in question. It can vary between just getting the source files and building them yourself, just like you do with your own stuff, to just using the public headers plus the relevant static/shared library. Most of the time, you'll want the latter. The right thing to do in 2020 in that case is IMHO to integrate with a source-based build system like vcpkg, portage (see the prefix project), conan, macports etc. Once the dev-env setup script boils down to just a list of packages, the question of importing third-party dependencies stops being a pain. I've used most of these (except conan) and vcpkg seems like it's the most painless one, especially because it's a CMake-based system and FWIW CMake seems to be what the C++ world is converging on these days. From my bubble anyway.