Is there any explicit application of Langlands conjecture for $\mathrm{GL}(n)$ for $n\ge 3$, to get some reciprocity laws for higher dimensional varieties or higher genus curves?
I've never found such things in articles such like "What is a reciprocity law?", Ana Caraiani's "Higher-dimensional reciprocity laws" or "Reciprocity laws and Galois representations: recent breakthroughs".