Sure, but none of that has anything to do with policy, nor do I think him wearing a mask would do all that much to get his base on board.

Basically, he was against masks, in favor of social distancing, and urged rapid development of vaccines (Pfizer vaccine was available around the end of 2020). He took and recommended others take the vaccine as well.

It's impossible to know exactly how Clinton would've responded, but I imagine it would be quite similar, with a bit less rhetoric and perhaps a little more distancing at rallies, just given what Biden did (but it's hard to say exactly, since mask-wearing became a form of speech).

So the main difference I see between Trump and Clinton/Biden is optics, not policy. And given the death rates between states (e.g. Florida vs California), there isn't a clear difference based on the party that was in power, and differences are more easily explained by climate, population density, and demographics. So sure, you can probably point to cases where people contracted COVID at a rally or something, but in terms of policy, there doesn't seem to be much difference between left and right on the COVID response outcomes.

So all in all, I think Trump's rhetoric around COVID was terrible, but I don't think it's fair to pin those deaths on him because they likely would've happened had he lost in 2016.