Can’t update iPhone 6 to 14.8

That's right. iPhone 6 is now nearly an 8 year old iPhone, which lacks the hardware required for any of the newer iOS versions. Your phone won't ever be able to run anything higher than iOS 12.5.x

If you need higher iOS versions, you will have to invest in a newer, more modern iPhone.

An iPhone 6 isn't capable of 13 or above.

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