should I upgrade to iOS 16 from 15

Hello and welcome to the community 🤗

To update your iPhone to iOS 16 (you can update from iOS 15 sure) follow this steps:

Update iPhone

• Firts back up your iPhone (for sure) How to back up your iPhone, iPad, and iPod touch - Apple Support (CA)

• After your back up Update your iPhone or iPad - Apple Support (CA)

• also, you can use your computer to update your iPhone. Look here for macOS Catalina or later Update your iPhone, iPad, or iPod touch with the Finder - Apple Support (CA)

• look here if you for macOS Mojave or earlier or on your Windows PC Update your iPhone, iPad, or iPod touch with iTunes - Apple Support (CA)

To install iTunes on pc look here Download and use iTunes for Windows - Apple Support (CA)

• You can also look this video

If your iPhone won’t update

• make sure you have 50% or more, you are connected to Internet and your iPhone is connected to a power source.

• Look here if your iPhone won’t update If your iPhone or iPad won't update - Apple Support (CA)

• try to update your iPhone with a Mac or pc.

• if this not work contact Apple Support

Note : the last version of iOS is iOS 16.0.3

For more help or questions

Come back us or contact Apple Support