iOS 12.5.2

Use a computer or the Software Update function in Settings. If you encounter a specific issue, describe it in this thread.

(196770)

These are the instructions:--> Update your iPhone, iPad, or iPod touch – Apple Support

If you have troubles, see this support article:--> If your iPhone, iPad or iPod touch won’t update

If the issue persists, contact Apple Support directly, using this link:--> Get Support

Regards

Giulio