The vast majority of Americans both already know how they feel about Trump and Biden and live in a solidly red or blue state. If you do want to focus on Biden, volunteer with phone banking or canvassing so that your efforts are directed to where they’ll actually matter and be organized in line with their messaging. Personally, I’d say you’re better off focusing on local races where you have more of an opportunity to come at it from a different angle and cut through people’s fortified positions. And as another user said, focus on mobilization, it’s easier to get someone who already agrees with you to register and make a plan than to convince someone to change their whole worldview.
There are also strategies outside of electoralism, such as protests and counter-protests. You can join an organization and form tactics and strategies to subvert the right’s actions, and engage with direct action to build trust and community that could be important in the future. Form strategies while being realistic about your goals and capabilities and coordinate with others.