That's not quite how it works.
Deadband is one of the things you can configure for each Monitored Item when created: DataChangeFilter – OPC Unified Architecture – Part 4: Services
It's a contract between the OPC UA client and sever, not necessarily anything to do with devices.
We could expose this as a Tag Group property and have all Monitored Items for all tags in that group get created with the same deadband value. It's just not something we're doing, and it wouldn't effect the underlying sampling from that device in any way, just the traffic between client and server.