How can I sync text deletion between iPhone and iPad?
How to delete text on iphone and ipad simultaneously?
[Re-Titled by Moderator]
iPhone 13 Pro, iOS 18
Assuming that both your iPad and iPhone and signed-in to iCloud with the same AppleID (now known as your Apple Account) - and you have enable iCloud Messages on both devices - deletion of a message on either device will be synchronised with the other:
Settings > [Your Name / AppleID] > iCloud > Messages > Use on the iPad | iPhone - set to ON