Hi 4TNnJuVg,
We understand that you're unable to update apps in the App Store. To clarify, do you experience the same issue when trying to download an app as well? You've completed some great steps so far.
Let's also be sure you're running the latest software version.
This can be found in Settings > General > Software Update. If so, be sure to secure your data with a backup: Update iOS on iPhone
If the latest software version is installed, we suggest reaching out to Apple directly. Depending on your region, you may be able to contact them here: Get Support
Best regards.