Yes, Samsung A12 is in the list for Android 12 and One UI 4. Just be patient. Chillax.
FYI, Samsung software update is actually come base on batch by batch. Meaning some country will receive it earlier and some might be a little bit late. This is normal and is a trend for Samsung for many years. Don't have to be worry because you will surely get the update.
Even a Samsung S series, the update are also the same. It will be release batch by batch. Or you can say it like market by market.