Trump is definitely more authoritarian than libertarian. However, I think why some think he is libertarian is because of relative comparison. For example, some parts of the left have become severely authoritarian, from anti-free speech ideologues to ‘tankie’ socialists, they don’t have a libertarian bone in their body at all. This ‘normalization’ of extreme authoritarianism leads to Trump looking libertarian by comparison. But then, Biden would also look positively libertarian under this standard!