As has been mentionned already, it's a draw because with the symetrical pawn structure and only a knight and king left on the board, there is simply no way that either side can create a threat which the other side cannot counter with accurate play. There are simply no deep ideas left in the position which a grandmaster at Ian and Magnus' levels wouldn't imediately see through and guard against.
As far as playing out the game, here's a link to one of Stockfish's suggested move patterns (depth=20).
[FEN "8/pp6/2pk1n2/3pN3/3P4/2P1K3/PP6/8 b - - 0 1"]
1... Ke6 {0.00} 2. a3 {0.00} 2... Ne4 3. c4 {0.00} 3... Kd6 4. Kd3 {0.00} 4... Ke6 5. b4 {0.00} 5... a6 6. c5 a5 {0.00} 7. bxa5 Nxc5+ {0.00} 8. Kc3 Ne4+ 9. Kb4 c5+ {0.00} 10. dxc5 Kxe5 11. c6 Kd6 12. cxb7 Kc7 {0.00} 13. a6 Nd6 14. Kc5 Nxb7+ 15. axb7 Kxb7 {0.00} 16. a4 Ka6 17. Kxd5 Ka5 18. Kc5 Kxa4 19. Kd4 Kb4 {0.00} 20. Ke5 {0.00} 20... Ka3 {0.00} 1/2-1/2
Hope it helps!