Why Warspite could not replace destroyers in the fjords

Could Warspite have taken on the German destroyers single-handedly in the PQ 17 scenario?

Probably in an open engagement, but the German destroyers could hide in fjord waters that Warspite could not reach and that British destroyers could still enter.

Warspite's armor and heavy guns would give her a decisive advantage if the German destroyers accepted battle in open water. The tactical problem was finding and holding them, not merely defeating them. Constricted or shallow parts of the fjords offered refuges that the battleship could not safely enter. British destroyers therefore remained essential because they could pursue enemy destroyers into waters denied to Warspite.