Hello raphael261,
Thank you for posting in the Apple Support Communities. I understand that updating your iPhone 7 is taking longer than expected, and I’d like to assist you.
First, the time it takes to update your device depends on the size of the update and your Internet connection speed. Try connecting to another reliable Wi-Fi network to see if that speeds things along. From there, taking these additional steps may help: Get help with over-the-air iOS updates
Additionally, you can try updating your iPhone via a computer: Update your iPhone, iPad, or iPod touch
Be sure to back up your personal data to iTunes or iCloud before updating. Here’s how to backup: How to back up your iPhone, iPad, and iPod touch
If the issue continues, I suggest using this resource: If you can't update or restore your iPhone, iPad, or iPod touch
I hope this information is useful. Kind regards.