Software
Why is my iPhone not showing software updates.
Why is my iPhone not showing software updates.
Depending on your iPhone model, the built in hardware may not support any further iOS updates.
Update your iPhone, iPad, or iPod touch - Apple Support
For example, any iPhone prior to the iPhone 6s can't be updated to iOS 15.
Check these articles about it:
iOS 15 and iPadOS 15 are compatible with these devices - Apple Support
iOS 14 and iPadOS are compatible with these devices - Apple Support
iOS 13 and iPadOS are compatible with these devices - Apple Support
Depending on your iPhone model, the built in hardware may not support any further iOS updates.
Update your iPhone, iPad, or iPod touch - Apple Support
For example, any iPhone prior to the iPhone 6s can't be updated to iOS 15.
Check these articles about it:
iOS 15 and iPadOS 15 are compatible with these devices - Apple Support
iOS 14 and iPadOS are compatible with these devices - Apple Support
iOS 13 and iPadOS are compatible with these devices - Apple Support
Software