First of, Trump is not a Republican. He is Trump. Secondly, Trump has had since his first mandate a nefarious effect in politics worldwide, and he is in part why the far-right and nationalistic movements across the globe, are also rising, through the spread of misinformation on the Internet, that transcend US borders. While I was very well aware that there was a thing like anti-vaxxers in the US, that was never a problem here in Europe, and the rise of misinformation, with the pandemic, and with Trump and the MAGA movement, that became a thing now here, along with other conspiracies on Facebook, like the “Moon landing being a staged hoax”. Retired boomers, that have nothing better to do all day, gobble up that shit as if it is ambrosia!
While you are right, Trump allowed that shit to be amplified and legitimizing it. The republicans (at least the more sensible ones) always knew that part of their electorate was into rabid conspiracies, but they would at least town things down, and did not allowed that shit to get much traction. With Trump, that become their bread and butter. Alternative facts, fake news, and all that shit!