Do not chase Android 14. Install LineageOS 18.1 (Android 11) or /e/OS . You will get 4+ hours of screen-on time, a snappy interface, and modern app support. The A5 2015 refuses to die, thanks to the dedicated developers on XDA.
: Based on LineageOS but with extra customization options. Getting Started samsung galaxy a5 2015 custom rom
For those wanting a completely different mobile OS experience, though it is more experimental. Essential Preparation Before starting, ensure you have these tools and files: How to Install a Custom ROM on Any Android Phone (Example Do not chase Android 14