Yes.
Just by looking at an artifact we cannot say that
it was designed. We assume design based upon experience
of designed objects, but that's not the same as formally
determining that something was designed.
We assume that the great pyramid was designed since it conforms
to our knowledge of 'designed' buildings/structures. It is composed
of blocks (which we know are used by people in construction) and
possibly we can still detect some tool marks on the stones.
It's still an assumption not a strict determination. It requires
KNOWLEDGE that such things ARE designed.