Yes, the Constitution specifies that the state legislatures have plenary power to award electors, and each state legislature has through statute created schemes whereby Electors are chosen by popular vote. Each state, again by statute, has designated the Governor as the person to certify the slate of Electors and to transmit the results to Congress.
So the Constitution designates the state legislatures with appointing Electors, and the state legislatures have enacted statutes directing how those Electors are to be chosen.
The Electoral Count Act is the U.S. legislature designating how Electoral vote results are to be tallied, and how to resolve disagreements.
But, wasn’t it argued by Pres lawyers that the legislatures can take that power back any time they want to? The state statutes cannot have precedence over the constitution. Also I believe Prof John Eastman said the same thing.