The wings -and especially the wing tips- couldn't possibly have had enough mass or strength to penetrate a healthy WTC wall.
But then, let's remember that the exterior columns of the towers were all clad with aluminum "siding" with insulation behind the siding. Thus, the wings would have left the IMPRESSION of penetrating the columns even if the columns behind were undamaged. However, there should then have been wing debris hanging on to the columns, sticking out or falling down to the ground. There was absolutely NOTHING protruding from the walls.
If the wall sections had been weakened in advance, it might be possible that the wings simply "bumped" the wall sections inward ... which would still leave the cut lines of the wings on the hanging aluminum siding.