Not sending I message messages
When I want to send a iMessage to my friend, it won’t let me. What should I do?
iPhone SE, iOS 14
If you can't send or receive messages on your iPhone, iPad, or iPod touch
Some things you can try. 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.
Restore - If you see an error when you update or restore your iPhone, iPad, or iPod
Backup - Restore your device from an iCloud or iTunes backup.