For a free, usable experience, install LineageOS 16 (Android 9) on your S2. It has 90% of Android 13’s core features (dark theme, permissions manager) but runs twice as fast.
Thanks to a dedicated developer known as (and the legacy team at the Galaxy S2 Unified Development forum on XDA), there is an official build of LineageOS 20 for the GT-I9100. samsung galaxy s2 android 13 free
Android 13 is the final version of the operating system to support the ARMv7 architecture For a free, usable experience, install LineageOS 16