airline · 1 tier tracked · 1 free way in, 0 conditional
The only way into Sun Country Rewards Plus status right now is the Sun Country Airlines Visa Signature card, which carries an $89 annual fee. Put $10,000 on the card within a calendar year and you earn Plus; the card's terms also let you skip the spend and instead fly 10 Sun Country flights in that same calendar year if you'd rather earn it in the air.
Neither route is free once you factor in the fee — even the flight-based option requires holding the card. There's no separate free path to Plus at this point, so the choice comes down to which condition fits your travel pattern: hit the spend threshold or log the flights.