How can I update my iPhone 7 to the iOS 16

I have iPhone7 model A1660

my employer requires my upgrade to =>16.0 in a few weeks.

A 2022 post same title says max for 7 is 15.7.1 but I just updated to 15.8 very recently (days ago)

So this 15.7.1 information is no longer valid, then maybe statement that 7 can't up to 16 is false too

But since I already updated just days ago and it 'only' gave me 15.8 how do I force it to up me to 16