Summary: The Samsung Galaxy S2 (released 2011) is no longer officially supported by Samsung and cannot run Android 13 via official updates. However, you can often install newer Android versions for free using unofficial custom ROMs from developer communities (e.g., LineageOS, AOSP-based builds). Below is a concise, actionable guide covering feasibility, risks, prerequisites, and step-by-step instructions to install an unofficial Android 13 build.