Peak seasonal flu in a bad season might infect 5% of a population at once. Most people don't get any single flu strain due to pre-existing immunities and the resulting slow spread of the virus. COVID-19 can be vastly higher, no one has any immunity.

The only real hope here is to prevent infections via quarantine measures, there is absolutely no way to build out the kind of health care capacity that would be needed in a pessimal outbreak.