How can I back up my phone

Hello war178!

There are three methods of backing up your iPhone that you can choose from: How to back up your iPhone, iPad, and iPod touch - Apple Support.

As for updating your device, your iPhone 6s Plus can be updated to iOS 15.7.7.

However, if you’re not there yet, please tap here to learn how to update your iPhone. 

👉 Updating/upgrading your iPhone 

If your iPhone won’t update, please see: If your iPhone or iPad won't update - Apple Support. 

👉 https://discussions.apple.com/docs/DOC-250003031

👉 If you see error 9, 4005, 4013, or 4014 when you restore your iPhone, iPad, or iPod touch - Apple Support

I hope this is helpful. Good Luck!

war178 Said:

"How can I back up my phone: I want to update my phone and do backup again"

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Updating an iPhone 6s:

Update Using a Computer:

Use my User Tip: Update your iPhone Using a Computer - User Tip. If any update are available, they'll install, sure enough.