So my question is, will the galaxy a50 get android 12 and above or is it stuck on android 11. If so how can I get a custom ROM on a50, and how do I open the boot menu on a50
No it won't be updated beyond Android 11 One UI 3.0.
It has the Exynos chipset, so if you go into Developer Options, and if you see "Unlock Bootloader", then you should be able to Flash Custom Roms.. But if you don't see any option to unlock the Bootloader, then no you can't Flash Custom Roms.
