You don't have to plan for a pandemic specifically. Just any kind of a downturn where you might not be making money for months at a time. It's called an emergency fund.
You always hear how people at home should have 6 months worth of expenses saved up in case of emergency. I'm honestly blown away how many businesses don't do the same thing. Basic fucking financials.
I understand a bit more if you're a smaller business, with small margins, and you're just getting started. But if you've been in business for years, with tons of money flowing through... and you can't get through a few months, maybe you should go out of business.