Okay, during the American Revolution and War of Bavarian Succession, Gustav III got ideas. And when absolutist monarchs (I prefer the term dictator but recognize most people consider it inappropriate) get ideas, they usually involve invading neighboring countries. While urging France to itnervene in Bavaria in 1778, Gustav III debated going to war with Denmark to occupy Norway. Indeed, government ministers submitted a long memorandum to that affect in 1779.
Creutz enthusiastically urged such a course in a long memorandum submitted on November 24, I779. By I783, the conquest of Norway had become Gustav's dominating interest and Creutz was called home to become foreign minister, in which capacity he served until his death two years later.
(He also considered invading the Empire to retake Verden and Bremen).
Suppose Gustav had decided to go to war with Denmark?