Samsung continues to update more devices to One UI 3.1 — here's the complete list - Android Police
One UI 3.1 has been rolling out to older Galaxy devices quickly in the last few monthsOver the last few weeks, One UI 3.1 has arrived for several mid-range devices and some T-Mobile variants
Although some features will remain exclusive to the S21, this is still a substantial update, especially for devices that were updated straight from One UI 2.5