ipad text messages

This support page may provide the answers that you’re looking for:

https://support.apple.com/en-us/HT208386

The key take-away points are likely to be that you need to explicitly enable Text Message Forwarding to your iPad on your iPhone - and enable Messages in iCloud on both your iPad and iPhone.

On your iPhone:

Settings > Mobile Data > Text Message Forwarding - set to ON - and explicitly enable your iPad from the device list

In your iPad and iPhone:

Settings > [Your Name / AppleID] > iCloud > Messages - set to ON

Hello,

Try disabling iMessage in Settings > Messages then re-enable it.