That is already turned on. Without it being turned on, it is obvious that no iCloud tabs will show up- even after force closing the Safari app and reopening it.Noticed I got this further down in a new window. After clicking ”Turn on” it appears to work ok. Looks like a privacy thing. View attachment 2430143
Even after turning it on, one needs to force close the Safari app and then reopen it to view the iCloud tabs from other devices.
This happens on all Apple devices using same Apple account- macOS, iPadOS, iOS.