You iPhone model (6 Plus) is incompatible with iOS13 and/or iOS14and/or iOS15. This is because your iPhone model (6 Plus)does not meet the hardware requirements for this iOS version(s).
You iPhone model (6 Plus) is incompatible with iOS13 and/or iOS14and/or iOS15. This is because your iPhone model (6 Plus)does not meet the hardware requirements for this iOS version(s).