Administration firing CDC officials in China designated to help identify potential pandemics: https://www.google.com/amp/s/www.mercurynews.com/2020/03/26/trump-administration-slashed-cdc-staff-inside-china-prior-to-coronavirus-outbreak/amp/
Failure to ramp up testing: https://www.google.com/amp/s/www.nytimes.com/2020/03/28/us/testing-coronavirus-pandemic.amp.html
Miscommunication between CDC and state health departments: https://www.propublica.org/article/internal-emails-show-how-chaos-at-the-cdc-slowed-the-early-response-to-coronavirus
The chaos surrounding the return of Americans abroad following his announcement of the expanded travel advisory: https://www.npr.org/2020/03/15/816065950/travelers-greeted-with-hours-long-airport-lines-as-coronavirus-screenings-begin
The aforementioned firing of the pandemic response.
Now, the above examples are more about the administration writ large. I don’t know how much of a role POTUS directly had in any of them.
His personal main fault is absolutely the inconsistency of messaging and downplaying the potential crisis, instead of confronting it head on. Remember the “we only have 15 cases, it will go down to 0, it’ll be a miracle.”
Also, he absolutely should have been pressuring red state governors to enact stay at home restrictions earlier. DeSantis leaving beaches open is inexcusable. Now, that’s not directly Trump’s fault, but he should have been using the bully pulpit on his own party.
Also, before I get accused at blaming the wrong people, the Chinese government is absolutely responsible for the bulk of this from their cracking down on health care workers speaking up, potentially misleading the world about the number of active cases, and, most importantly, continuing to let wet markets exist.
But that doesn’t excuse our own government’s mishandling.