What is your planting zone? Depending on the variety, if you leave it outside in the elements, it will simply go dormant in the winter. I'd protect the pot with some kind of thermal blanket. Apple trees grow in ground and their roots are more protected there.

Permanent planting would be best...then see what fruit you'll end up, most likely a tart little crab apple,...perhaps you can graft it over if you don't like it.

Oh yeah sorry I'm NYS so even though it's so small I should plant it outside? U don't suggest bringing it inside?

Aren't there apple orchards in your state? Again, it depends on the variety. My Anna apple trees would die in your climate, and a variety that needs winter chill would die here. Apple trees are not known to be house plants.

Make sure to put plastic tree wrap on it or mice,rabbits, or shrews might girdle it

Plant outside is best, no worries..seedlings are hardy crab apples most of the time.