The update comes with a redesigned UI, improved performance, and better customizations. It also brings an enhanced Samsung Keyboard and stronger privacy protection in addition to the May 2021 Android security patch. You can head this way to learn more about the update.
The One UI Core 3.1 update has firmware version P205DXU5CUE2 and requires a download of about 1.6GB. It’s seeding in the Philippines for the LTE variant (SM-P205) at the time of writing this, but the rollout should expand in other countries soon.
Thanks for the tip, raznek91!