My I cloud mail will not load and when I go to iCloud. Com. It says unable to load
iPhone 8 Plus, iOS 12
Mail – Setup and Troubleshooting on iPad
Do you have access to another WiFi network where you can try? That has worked for several people.
Try a restart.
Restart your iPhone, iPad, or iPod touch
Try a forced restart.
If necessary
Do a backup and try a factory reset. Then restore from your backup.
Backup - Restore your device from an iCloud or iTunes backup