Preparing for Day X - what belongs to IT emergency planning?

No organisation is safe from cybersecurity attacks. The IT emergency is not entirely avoidable, but the amount of damage it causes is. Whether your business starts up again within a few days or comes to a standstill for weeks can mean your very existence. Ideal conditions for blackmailers to extract high ransoms.
The increasing networking of machines, devices and IT infrastructures as well as pandemic home offices have multiplied cybersecurity attack surfaces and risks. Organisations, companies, public authorities, hospitals, retirement homes, universities or critical infrastructure facilities need cybersecurity as the basis of digital sovereignty.
How can organisations respond to cyber risks? How do you prepare specifically for an attack without the effort of a BSI basic protection or an ISO 27000?