It seems likely that if the national response to covid had tracked with, say, the NY State response, that yes: we'd have seen far fewer deaths. The first 60-100k, mostly in the northeast, probably couldn't have been saved. The initial outbreak happened too fast and too hard. But after that, NY has been flat. They controlled it. The same could have been true for the rest of the country, yet we collectively chose not to.
And yeah, that national response is the job of the executive branch. So very roughly 150k americans are dead now because Trump was in office. Somewhere around there.