How to Install LineageOS on Samsung Galaxy S9/Galaxy S9 Plus
This is Noble rom, an android 12 custom rom for the Galaxy Note 9 and S9 by AlexisXDA on XDA. It has some bugs but nothing that's deal breaker, some stuff have
10 Best Custom ROMs for the Samsung Galaxy S9 - JoyofAndroid
Bliss ROM With Android 12 For Samsung Galaxy S9 Plus (Star2qlte) | The Custom Rom
Android 12 Custom ROM Download: Xiaomi, OnePlus, Samsung, Oppo, Vivo and more
Developer Releases Android 12 Custom ROM For Galaxy S9 & Note 9