Primary devices no longer need to be logged in to any linked secondary devices to run WhatsApp. The app-owned company Meta Platforms has recently announced to open the feature to everyone after running test-audits for the past few months. It can be launched in both Android and iOS operating systems.
For the feature, you have to enter the beta option of Linked Devices first. Then users can start it. If it is launched, it will be unlinked from all linked devices. Gotta link it again. If it is newly linked, then it is okay if it is not linked to the original smartphone. All devices will have call and chat end-to-end encrypted at the same time.
The news media GSMArena says it can work up to 14 days after being disconnected from linked devices. But even if this opportunity is in iOS, users cannot delete any message from linked devices.
No tablet from iOS or any other smartphone can be connected like this. To use the feature you must have the latest version of WhatsApp.