WideCharToMultiByte std analog UTF8

This code is workng properly for me:

std::wstring wmsg_text = L"ｷｴｵｲｳｶｸｹｺｻｼｽｾｿﾀﾁﾂﾃｱ";
char buffer[100] = { 0 };
WideCharToMultiByte(CP_UTF8, 0, wmsg_text.data(), wmsg_text.size(), buffer, sizeof(buffer)-1, NULL, NULL);

I wonder the cross platform analog of this code. I look to std::wcstombs with std::codecvt_utf8, but can't guess how to use this by right way.