You're looking for a custom ROM for your Sony Xperia 5 III. Here are some pieces of information that might help:
Custom ROM options:
If you are a photographer who relies on Sony’s Photo Pro and Video Pro apps: sony xperia 5 iii custom rom
Install a custom ROM if:
Do it if: You are comfortable with command lines, you want Android 14/15 features, your phone is out of warranty, and you don't mind using GCam for photos. You're looking for a custom ROM for your Sony Xperia 5 III
Display Features: Support for the 120Hz refresh rate and 21:9 aspect ratio is standard in most stable builds, though Sony-specific audio tuning algorithms (like DSEE Ultimate) may be lost. Stock Sony camera app will crash