Oh, that's simple! They didn't have one. Otherwise we'd not have outbreaks in every single state.
That's why we had huge numbers of nursing home deaths early on; They panicked and thought putting sick old people in with other confined old people was a good idea, rather than putting them in predesignated emergency facilities.
That's why we have a shortage of hospital beds even now; hospitals generally run at about 60% capacity, and since there were no predesignated plans to rapidly increase bed capacity and nurse count in a crisis we've had critical shortages of both in almost every state.
That's why they had no reserves of PPE, ventilators, or enough emergency cash to procure them. They had to go to the Feds for help (and the Feds mobilized the most effective PPE and ventilator production chains we've ever seen, as well as throwing $6 trillion at the outbreak.
Trump and Congress' job was to keep the virus out of our borders. Once that became an impossibility, for a myriad of reasons, legal authority shifts to the governors of each state. It is their responsibility, not that of the President or Congress, to have a response plan ready in times of crisis. They're in charge at that point. All the Feds can do is respond if the states file a request (which many did), and they (the Feds) were very effective at that.