General Troubleshooting/Info

Stock Android Version

1. Both Lineage OS 20 and Pixel Experience 13 need you to be on OneUI 5 bootloader.
   
2. To do this, you have to install on top of OneUI 5 stock rom. 
3. If you have OneUI 4.1 or earlier installed (before you installed any other custom rom), you can either download stock rom from something like samfw or sammobile, and then repeat all the steps from the preinstall page, or simply download the latest AP, BL and CP files from HERE and flash them in their respective slots in Odin. Using this second method will not get rid of your custom recovery either.
4. If you try to flash the latest ​Pixel Experience 13 or Lineage OS 20 update and get an error in recovery while flashing it saying "ERROR: This package requires Android 13 based firmware. Please upgrade firmware and retry!" you need to do the above steps.