https://www.gamespot.com/articles/free-ultra-sun-and-moon-items-come-to-pokemon-go/1100-6454914/

Pokemon Go is adding new customisation items to celebrate the soon-to-launch Pokemon Ultra Sun and Moon. As announced on Twitter, you can now dress up your character in Alola region outfits.

You can see some of the new items in the image below. The items are free, and they include things like a sun hat, sandals, and shorts, among other things.