As long as they're connected to a wall socket. Otherwise, citation needed. Power Management in hard. Who does the myriad of hardware quirks for OpenBSD?
If you are referring to suspend/resume, then OpenBSD has great support[1]. Its one of the very few ACPI stacks not derived from Intel's ACPICA reference code.
Would you like to explain that, and maybe cite some references?
Suspend and resume have been stable for me as long as I've had a computer capable of supporting them.
And I'm not aware of any way to make them fail without doing something obviously intended to disable them.
Reference: Every time I've tried Linux on a laptop, Suspend, Resume, or Both has been broken in whatever $FLAVOR_OF_THE_MONTH distro/package/kernel the community insists is the next big thing.
The BSDs tend to implement these things later but far more reliably.