Need to install new software to my apple
How can I upgrade my phone
iPhone 6 Plus, iOS 12
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You can follow the steps at the link below to update your device.
Update your iPhone, iPad or iPod touch – Apple Support (UK)
Please be advised, as you have an iPhone 6+ the latest version of iOS would be 12.5.5. You are unable to upgrade to the latest version of iOS which is currently iOS 15. Sadly iOS 12.x is as far as your phone will go.