As A Owner Of The Fairly Old Samsung S9 (Android 10) I Have Seen The New Samsung OneUI3 & 4 And Android 11 & 12. But! Unfortunately I Can Not Update It Which I Think Is A Bit Mean As Offcorse The New Software Aswell As New Features And Design It Has Also Included Better Software And Hardware Management (Atleast Better Then Previous Software Versions). So I Think Considering That The New Samsung S21 & S22 With 4 Year Of Updates I Think My Phone/Every S9 Could Have Gotten Another Year Of Software Updates To Push It To Android 11
You really really really don't want One UI 4. Its a massive downgrade. Completely awful UI. Huge downgrade on my Note 10+ 5G. Makes a £1000 phone I'm still paying for for a year look like an entry level budget model, makes a 4K screen look like a 480p sub vga iPhone 3. Weather icons ruined and useless, battery life worse even after a cache clear, font especially 9/6 numbers hard to read, fisher price charge icon. Best advice is dont' upgrade for as long as you can.