TheAGames10 Sadly, your device cannot support GOS, but in addition, installing an alternative operating system on Samsung devices blows a fuse (e-fuse) and prevents you from using the operating system with its security features intact, even if you revert to the original operating system, the device becomes unusable and you lose your warranty.
If you really want GrapheneOS now, you can try selling your Samsung Galaxy A16 and getting a Google Pixel 9a or 10a, or even a used Pixel 8a which still has 5 years of full security updates, it's worth it.