My device has not gotten the android 12 updates.. it's still on one ui 3.1
Android 11 and haven't received any updates since months
how can I get all the missed updates ?
This should be available on the phone's software update section to update @Imran444
Maybe try Samsung Smartswitch.
If the phone was supplied by a network then ask them as some networks control the distribution of software.
If a phone has been imported from one country to use in another then updates can occasionally take longer to come through as your reliant on the Samsung Servers of that region.
If the phone is unlocked to all networks try inserting another networks sim card which can sometimes instigate an update.
Another option is to visit a Samsung Experience Store or Samsung Service Centre who maybe able to help.
I wish you all the best. 
