Android 12 is the latest version of Android. It is still not available on compatible smartphones. But it does not stop developers from doing experiments on it. Samsung Galaxy S3 is an old smartphone, released in 2012. After Android 4, it does not get any software updates so far. So Android 4 is the last version that Samsung Galaxy S3 can get.
The Galaxy S3 so far unable to run the latest Android, like Android 12?
This is the question asked by the developer calling himself html6405. In your case, your answer is probably no, because it cannot handle the Android 12 Update.
In a video, by html6405, we can see LineageOS 19.0, which is an UnOfficial Android 12 ROM. With the excellent performance of its time, it manages to run Android 12.
The camera, WiFi, Bluetooth, or even accelerated video playback works perfectly. That being said, it is also necessary to underline the absence of some functionalities, which is explained by the still recent availability of LineageOS as well as the hardware limitations of the smartphone. It also requires the presence of some bugs. In particular, it is impossible to unlock his SIM card with his PIN code. The NFC module also does not work, as well as formatting of the SD card.
Also Read: How to Properly Uninstall Video/GPU Drivers