Point to note, iCloud messages will sync things for iMessages only but not normal green SMS. I have this turned on and iMessages are deleted from my iPhone\Apple Watch if i delete from the other device but i have to delete green SMS messages from both.
That’s not the behavior for me. If I delete an sms thread on one of my devices it deletes on my other devices as well. Just tested it. Both iMessage and sms sync with iCloud.
The limitation is when you delete texts (SMS) on an Apple Watch, that deletion doesn’t take affect on other devices, and vice versa. For whatever reason Apple (being the useless idiots they are) decided that the watch didn’t matter when it came to text message deletions and synchronisation.
Make sure Messages in iCloud is enabled on all of your devices.
“When you delete a message, photo, or conversation on one device, it’s removed from all of your devices.”
Set up iCloud for Messages on all your devices
Learn how to set up iCloud and access your messages on your iPhone, iPad, Mac, and Apple Watch.support.apple.com
Does the highlighted part actually work? It never did for me. It just removed the photo from device A but the photo was still sitting there in the iCloud as well as on device B with no idea how to actually remove it. One of the reasons I stopped using iCloud Messages - storage hog
Is there a way to delete texts across all iOS devices or do I have to delete them from each device separately ?
still does not work for me. I can delete texts from device X and it gets removed on device Y but images remain and I need to delete them manually from settings > general > storage > messages on each deviceJust tested deleting a photo in a message from my MacBook and it deleted the photo in that message on my phone.
Also I have my message settings set so that messages are automatically deleted after a year. Keeps the storage size down but have enough message history if I need it.