Trying to update iPhone ti12.2

https://support.apple.com/en-us/HT204204

I also have the iPhone 6+ and the lastest update was 12.2 and after this year 2019 Apple will no longer update your iPhone because it is too old. Before the ending of this year Apple might do another update before the year ends on December 31, 2019.

AFAIK it is based on hardware capability not age and iphone 6 will be supported until it no longer has the hardware to support an as-yet unannounced new feature.

my ipad mini dropped off the perch because it is 32bit architecture not because it is too old.

By the way iphone 6 plus 32GB was only discontinued from manufacture in September 2018 so spare parts should be available to repair shops for 5 years after that date according to Apples normal policy and writing it off from updates in 2020 seems a tad early to me.

Unless someone knows different.

You do not know that for sure.