On the one hand, parking a freshly tinted car in a garage does give better protection. Conditions inside a garage are relatively stable, keeping severe weather and dust off the bodywork. A garage also cuts UV exposure substantially, so the film will not age or discolour from prolonged sun. For a new car or one that has just been tinted, garage parking is the best way to maximise the life of the film.
On the other hand, letting a tinted car sit in the sun has its own advantages. Warmth from the sun and the natural evaporation of moisture help water pockets disappear faster and leave the film flatter. Direct sunlight also speeds up evaporation, reducing the risk of water pockets blocking your view for days. Air-dry the car in the shade instead and those pockets can linger on the glass and obstruct your vision.
Both options have their merits, so the right call depends on your situation and environment. If you live somewhere with harsh weather or strong sun, or you are particular about how your car looks, a garage is probably the better choice. If the film has a lot of water pockets, a spell in the sun will resolve them faster.