Host of the 2028 Olympics, for short

USA

This country’s flag features fifty stars and will soon welcome the world’s top athletes.

The 2028 Summer Olympics will be held in Los Angeles, which is in the United States. "For short" signals that the answer is an abbreviation, so instead of "United States of America," you use "USA." It’s a straightforward clue where the key is recognizing the country hosting the event and its common three-letter shorthand.