Per title. I'm aware "great power" & "major concession" aren't well defined, so as long as some reputable historian calls them so that suffices for me.
There are plenty of examples where great powers make such concessions to other great powers (e.g. Treaty of Nerchinsk), but I can't think of examples where the country is significantly weaker than the great power. The closest is the Treaty of Addis Ababa that ended the first Italian-Ethiopian war, but the Italians were beaten in that war, so they weren't in a position of strength.
Something that would work would be if the British Empire had, just prior to the Second Boer War, agreed to the Boer ultimatums; or if the British Empire had decided not to prosecute what later turned into the First Opium War.