The Samsung A9 2018 is not dead for custom ROMs, but the Snapdragon 660 + Samsung proprietary camera stack limits it to a mid-tier custom ROM experience . Use LineageOS 20 unofficial if you prioritize latest Android and can sacrifice 2 cameras + VoLTE.
, which often produces better dynamic range than the stock Samsung app. Flashing custom software voids your warranty and trips Samsung Knox custom rom for samsung a9 2018