I grew up in a very conservative household. My father, son of a Missouri farmer, staunch lifelong conservative, and a PhD mathematician, was stubbornly anti-fact. He doubted medical opinion - and lost his teeth due to his dismissal of the efficacy of flossing - he doubted scientific findings on the danger of pollution and took up the side of industry - he doubted medical research outlining the dangers of smoking and its effects, including second hand smoke; and so on.
I think that science denial was widespread among the Right way before Trump as evinced by my father - Trump and the support he received from Fox and other right-leaning outlets simply made science denial socially acceptable if not admired. And from there, the floodgates of lunacy opened wide. The Right's "tent" of acceptable views burgeoned, to include conspiracy theorists and right wing radicals.
But the science denial mindset was widespread among conservatives and existed long before Trump.