Yes, extremism exists on both ends of the political spectrum. But I’d argue that American right wing extremism tends to result in greater losses of liberty for the poor, vulnerable and underprivileged.
American left-wing extremism tends to involve expanding freedoms or benefits to groups in ways some consider excessive (e.g., abortion, trans rights, gay marriage, universal healthcare, immigration) which can result in economic instability and friction in communities. However what America considers extreme left is generally moderate-center in Europe. The American left also has a tendency to label critics of iliberal policies as “deplorable”, "bigoted", etc- which shuts down meaningful conversation.
By contrast, American right-wing extremism, often seeks to dehumanise minorities and vulnerable groups, and actively strips away their rights, through policies and rhetoric reminiscent of the beginnings of fascism and segregation, for example:
Women: restricting abortion, undermining maternity rights, and promoting values/policies that limit women's career and lifestyle choices.
The poor: cutting access to healthcare and imposing tariffs without concern for economic impact; limiting employee rights
Black people & minorities: denouncing the civil rights movement, denying the legacy of slavery, using stereotypes to justify institutional racism and systemic bias (i.e. greater rates of incarceration of minorities for the same offence), and dismissing accomplished minority figures as mere “diversity hires.”
Immigrants: dehumanising immigrants through rhetorics that compares them to vermin and blames them for societal problems; deporting legitimate citizens and/or people who have contributed to American society for many years without issue; viewing white people as the only true Americans leading to different treatment of white and minority immigrants
Gun control: refusing to regulate firearms, even though the resulting deaths far outnumber those supposedly “protected” by the right to bear arms.
This is my view, but I'm sure many will disagree.