Have you tried going to security and privacy settings to see if an update is available? If you bought a used phone, I can see by the model # that it was an unlocked carrier version and you would need to either find a SIM card (working or non-working) from the original carrier or connect your phone to a computer and try to force an update through Smart Switch for computer. Can you share a screen shot of software information in the about phone section of your settings. Only the bottom half where it shows service provider software version will do. Then we can tell you which carrier was the original carrier. Be advised that if you manage to get the Android 16 update, it will be the last update the phone is eligible for.
Was it originally a carrier phone that you unlocked and are now with a different carrier? If that's the case, you would need to insert a working or non working SIM from the original carrier to get your updates. If you have a computer, you can try connecting your phone, downloading Smart switch for Windows and trying to force the update.
