Without Trump fucking shit up on a government level (the Supreme Court in particular), there would probably be less scary shit happening on that end. Would have slowed things down.
But the radicalisation of the Americans began before 2016. Trump is a symptom, not a cause. The disease started spreading as early as 2008. The recession, the damp squib that was the Occupy Wall Street event was the inception of many political movements, both far left AND far right.
That’s the thing people don’t realise. Even if Donald J. Trump didn’t exist, the underlying social tensions mean that inevitably someone would show up to galvanise far right sentiments, and the political estabilishment would have boosted them, whoever they were, because when the common folk are getting angry about their lot, then to the people actually in charge, a fascist dictatorship is preferrable to the alternative.