I fly the bus around Europe and our SOP's are when cleared to a FL (and out of SRS) we set STD. Similarly when cleared to descend to an altitude we set the QNH and the PF will cross check their altimeter by verbalising with the PNF. Something like 3,000 on 996 gives me xxxft. The PNF will confirm with a "checks" or something along those lines.
Our SOP's differ for flying in the US since the TL is much higher than what you find in Europe but its probably not relevant to your question.