Download the LineageOS 20 build and a "BitGApps" package (if you want the Google Play Store). Step-by-Step Installation Guide (Brief Overview)

The best place to find the latest, safest, and free versions of the Android 13 ROM for the Galaxy S2 is the . Search for the "GT-I9100 LineageOS 20" thread to find the download links and specific troubleshooting tips from the developers themselves.

Modern software is not optimized for such old battery tech.

Because Samsung stopped supporting the S2 over a decade ago, you won't find an official "System Update" in the settings. Instead, the transition to Android 13 is made possible via , an open-source custom ROM.