When I began playing chess I tried to make the 2 knights mate forced by forcing black king to capture on a corner square, for example - checking the black king with my queen on a8 so that black king is forced to capture it and thus forced to move on a corner square. But it's impossible to mate him then, because before I sacrificed my queen, the a7 square (where the black king was) had to be free of my attack from a knight. And then when you get his king in the corner, you have to cover a7 square with one knight and give check with other in one move.
My point is that there is no way to force black king in a corner and at the same time have knights on the right squares to deliver the checkmate:
A checkmate with two knights cannot be forced, but here it is anyway