Chat with name Esther

There is no undo or recently deleted option for Message conversations like there are for Photos or iCloud Drive files.

If you are not using Messages in iCloud, then a backup of your device would include those messages. The problem with that is iCloud backups overwrite any previous backup, so not only would you have to not be using Messages in iCloud, but there could not have been an iCloud backup after that was deleted and you would need an iCloud backup before it was deleted to restore your device. The result would be that you lose any new data since that backup. The iCloud backup is really not intended to go back in time to restore specific data, it is simply to mirror the device to its latest state in case you lose your phone or it is damaged, where you could then pickup where you left off on another device.

There's no one from Apple here. We're just users, like you, and we can't restore a chat.