A pithy response, to be sure, but rather lacking in any noticable thought.

The reality, as it stands, is that, baring any unforseen events, come January one of either Biden or Trump will be the president of the United States of America. This is, to put it mildly, suboptimal, however it is pretty much inescapable at the present time. Assuming you are elegible to vote in the upcoming ekection, any action, or inaction, on your part will have an effect on the totals. Whether that effect actually carries any weight will be down to whether you're in a swing area, which, again, is suboptimal but won't change between now and then.

The time to change these underlying facts is after the election, pushing one, or both, parties to change their policies for the next election, or even the one after. They can't/won't make actual, meaningful changes before November in fear of scaring their base voters, so change is going to be slow, and needs to start at the grassroots level. Persuade enough voters that the change you want is needed and they'll be more inclined to vote for those who support those changes.