Retrieving text messages

See the following from Delete and recover messages on your iPhone or iPad - Apple Support

Retrieve a deleted message or conversation

1. In Messages, tap Edit.
2. Tap Show Recently Deleted .
3. Choose the conversations with the messages you want to restore, then tap Recover.
4. Tap Recover Message or Recover [Number] Messages.

You need iOS 16, iPadOS 16.1, or later to recover deleted messages and conversations. You can only recover messages and conversations that you deleted within the last 30 to 40 days.

If the phone is running iOS 16, check this link...

Recovering deleted texts and iMessages - Apple Community

If that doesn't help, you are probably out of luck unless you included the messages in a recent back-up of the device.