How can I upgrade my iPhone

Ogbak wrote:

How can I upgrade my iOS

To learn how to update your iPhone click on this link:

Update your iPhone, iPad, or iPod touch

If you have a problem during the update:

If your iPhone, iPad or iPod touch won’t update

..Ogbak:

Should your iPhone actually be an iPhone 6 (not 6Plus, or 6sPlus)

That indicates the product is near the end of upgrades.

Last supported iOS (isn't iOS15.3.1) for an iPhone 6

Those only go to iOS 12.5.5 (16H62)

When that's the case, a later iPhone model could use Upgrade.

Some step updates may be out there yet; not much further.

To buy ahead of the Curve, without getting a new one, may be

OK. ~ But be sure you aren't only one or two steps, ahead of it.

[My first-edition iPhone SE is near end of the road w/ iOS15.3.x]