There has been nothing more damaging in modern America to civil liberties than the war on drugs, but it's largely happened to the poor and people of color so the damage is largely ignored. Meanwhile, I'm not exactly sure what Biden, specifically, will take away in terms of my civil liberties, but that is generic fear I hear under every administration, particularly when a Democrat takes change. Yet, my life is pretty much unchanged, as are my "rights", even when it was Clinton or Obama in charge, and I'll suspect the same for Biden.
I'll also say we are living in times with much greater levels of civil liberties than in the past, especially for groups on the margins, like gay folks, black people, women and so on. Of course, ever since I can remember, it's been fashionable to say all is going to hell and America will be destroyed by so and so or some particular group or idea. Yet, here we are, surviving quite fine.