Due to limitations of internal hardware, the new Stage Manager feature introduced with iPadOS 16.1 is only available for these models of iPad:
- iPad Air (5th generation)
- iPad Pro 11-inch (all generations)
- iPad Pro 12.9-inch (3rd generation and later)
Feature availability is usually limited by system hardware - CPU and available RAM being critical to some advanced functionality.
iPad models supporting Stage Manager have an M2, M1 or A12X CPU (upon which the M-series CPUs are reportedly based) - with at least 8GB RAM. The iPad Air4 has only 4GB RAM.
Whether or not a functionally limited version of Stage Manager, compatible with models of iPad that do not meet the current hardware requirements, will ever be released is unknown.