Here in Europe, a common "scheme" seems to be that a PPL embarks on a VFR flight, but carries a passenger in the RHS who has an IR, and this enables them to request an IFR clearance should they need one due to weather etc.
But only the qualified pilot can legal fly the aeroplane under IFR unless undergoing instruction
FCL.600 IR — General
Operations under IFR on an aeroplane, helicopter, airship or powered-lift aircraft shall only be conducted by holders of a PPL, CPL, MPL and ATPL with an IR appropriate to the category of aircraft or when undergoing skill testing or dual instruction.